No video captured what happened to Freddie Gray inside the police van where officers heaved him into a metal compartment after pinning him to a sidewalk. The cause of his fatal spine injury has not been revealed. But a troubling detail emerged as hundreds of protesters converged on City Hall again Thursday: He was not only handcuffed and put in leg irons, but left without a seat belt during his trip to the station, a police union's lawyer said. Unbelted detainees have been paralyzed and even killed by rough rides in what used to be called 'paddy wagons.' It even has a name: 'nickel rides,' referring to cheap amusement park thrills. 'Deadly nickel ride': Gray, 25, was arrested on April 12 in Baltimore and died a week later from a severe spinal injury that may have been caused when he was shackled and driven to the police station in a paddy wagon without being strapped into a seatbelt . 'Nickel rides' have caused spinal injuries in the past and Baltimore police epartment rules were updated nine days before Gray's arrest stating that all detainees shall be strapped in by seat belts or other device . Police brutality against prisoners being transported was addressed just six months ago in a plan released by Baltimore officials to reduce this misconduct. Department rules updated nine days before Gray's arrest clearly state that all detainees shall be strapped in by seat belts or 'other authorized restraining devices' for their own safety after arrest. Gray was not belted in, said attorney Michael Davey, who represents at least one of the officers under investigation. But he took issue with the rules. Gray died on Sunday, April 19, after he 'had his spine 80 per cent severed at his neck' while in police custody . 'Policy is policy, practice is something else,' particularly if a prisoner is combative, Davey told The Associated Press. 'It is not always possible or safe for officers to enter the rear of those transport vans that are very small, and this one was very small.' Assistant Police Commissioner Jerry Rodriguez said Gray was secured by 'leg irons' after he became agitated during the trip, but the department hasn't said whether he was buckled in with a seat belt. The Gray family's lawyer, Billy Murphy, said 'his spine was 80 percent severed' while in custody. It's not clear whether he was injured by officers in the street or while being carried alone in the van's compartment. But if it happened on the way to the station, it wouldn't be the first such injury in Baltimore: Dondi Johnson died of a fractured spine in 2005 after he was arrested for urinating in public and transported without a seat belt, with his hands cuffed behind his back. 'We argued they gave him what we call a `rough ride,'' at high speed with hard cornering, said Attorney Kerry D. Staton. 'He was thrown from one seat into the opposite wall, and that's how he broke his neck.' Staton obtained a $7.4 million judgment for the family, later reduced to the legal cap of $200,000. It also has happened in Philadelphia, where police in 2001 barred transportation of prisoners without padding or belts after The Philadelphia Inquirer reported that the city had paid $2.3 million to settle lawsuits over intentionally rough rides, which permanently paralyzed two people. Two arrests: Demonstrators block Martin Luther King Boulevard as they march to the Western District Police Station to protest the death of Freddie Gray in Baltimore on Thursday. As evening turned into night on Thursday, two protesters had been arrested for disorderly conduct . Rally continues: Protesters on Thursday night were continuing a rally at Baltimore Police station just blocks from where Freddie Gray was arrested . Charges: Demonstrators gesture towards police as they protest the death of Freddie Gray, an African American man who died of spinal cord injuries in police custody, possibly as a result of misconduct on the part of six city police officers . Members of the Baltimore Police Department stand guard outside the department's Western District police station during a protest for Freddie Gray on Thursday . Angela Hazel (C) reacts near City Hall during a protest against the death of Freddie Gray Hazel said 'I lost my child to the streets, too. My only child...' Gray fled on foot and was captured on April 12 after an officer 'made eye contact' with him outside a public housing complex, police said. Videos show Gray screaming on the ground before being dragged, his legs limp, into a van. Witnesses said he was crying out in pain. Kevin Moore, a friend of Freddie Gray's who recorded video of his arrest, told The Baltimore Sun that police had Gray's legs bent 'like he was a crab or a piece of origami.' On Thursday, demonstrators briefly scuffled with police while some threw bottles of water and debris at officers. Police said  one man was arrested for assault, and another for destruction of property during the noisy march from City Hall to the Western District police station. The march snarled rush-hour traffic and drew onlookers in Baltimore's Inner Harbor, its premier tourist attraction. Chanting 'Tell the truth! Stop the lie! Freddie didn't have to die,' protesters ended outside the Western District station facing off with police behind metal barricades. Protesters for Freddie Gray stand outside the Baltimore Police Department's Western District police station. The protest was peaceful, though some in the crowd hurled insults at the officers behind the fence, who stared back stone-faced . More than 50 officers manned a barricade surrounding the station, separating them from the protesters . Demonstrators march to the Western District Police Station to protest the death of Freddie Gray in Baltimore on Thursday as the days-long protest continued . The Southern Christian Leadership Conference said it would investigate Gray's death, and the local head of the civil rights group said it lacked confidence in a police probe. Police procedures require officers to get immediate medical help if detainees need it, and to avoid aggravating any injury. In Gray's case, he repeatedly asked for help during the trip, but the driver instead diverted to another location to pick up another prisoner. For the first time, the fire department released a timeline for paramedics' response. Gray was arrested at 8:42 a.m. Paramedics received a call for an unconscious male at 9:26 a.m., Baltimore City Fire Department spokesman Captain Roman Clark said. Medics arrived at the police station at 9:33 a.m., but didn't leave for the hospital until 9:54, arriving roughly an hour and 20 minutes after his arrest. Clark didn't say why it took more than 20 minutes to leave for the hospital once paramedics arrived. 'How did his injuries occur?' said Robert Stewart, a former chief who consults with police and the Justice Department on use of force. 'These guys are picking up someone who is obviously injured.' In video footage of Gray's arrest, he appears to be dragged to a police transport van by officers including bicycle cops . Not strapped in: The Baltimore Fraternal Order of Police Lodge 3 and lawyer Michael Davey, center, are facing criticism after  released a statement that described the citizens protesting the death of Freddie Gray as a 'lynch mob'. On Thursday, Davey admitted that Gray was not strapped into a seatbelt while he was being transported . Gray died on April 19  at the University of Maryland Shock Trauma Center from his spinal injuries . Many protesters have taken issue with the original reason for police stopping Gray, that he was running away . Demonstrators pretend to be arrested in front of the Baltimore Police Department Western District station to protest against the death in police custody of Freddie Gray . Captain Erik Pecha of the Baltimore Police Department exchanges words with young demonstrators . Demonstrators speak with law enforcement officers. The U.S. Southern Christian Leadership Conference will independently investigate the death . The driver also has a responsibility to refuse to take a seriously injured prisoner to the station if he belongs in a hospital, Stewart said. 'If I'm the officer in the wagon, if the guy's hurt, I'm not taking him,' he explained. All six officers involved in Gray's arrest have been suspended with pay while under criminal investigation. Davey, whose firm is on contract with the Baltimore Fraternal Order of Police Lodge 3, said five of the six officers gave voluntary statements the day of Gray's arrest, and one - he didn't say who - declined to speak with investigators. It's quite common for prisoners to yell and complain, saying they've been injured or feel sick or that their handcuffs are too tight. 'You have to make a judgment call: is this a tactic, something to distract me?' said Lt. Luis Fuste of the Miami-Dade Police Department. 'You're taught that these things are often done with an ulterior motive.' Tensions: Protesters gathered in front of the Baltimore Police Department Western District station . Hundreds took part in a demonstration in Baltimore overnight to make their voices heard . The march snarled rush-hour traffic and drew onlookers inBaltimore's Inner Harbor, its premier tourist attraction . Yet Fuste and other law enforcement experts say rough rides aren't typical, and aren't worth the trouble to officers. 'Once he is a prisoner he is absolutely your responsibility,' said Peter Moskos, a former Baltimore officer who teaches law and police science at John Jay College of Criminal Justice in New York. 'Even if there was no malign intent, even if there was no assault, he's your prisoner. He goes into the wagon alive, he can't come out dead.' The Department of Justice is investigating whether Gray's civil rights were violated, and an internal police investigation will be delivered by May 1 to the state's attorney's office, which will consider filing any criminal charges. But some details have already been made public as authorities try to restore trust with a community demanding transparency and justice. Commissioner Anthony Batts said Monday that officers repeatedly ignored Gray's requests for medical attention before he was hospitalized in critical condition. 'He asked for an inhaler, and at one or two of the stops it was noticed that he was having trouble breathing,' Batts said. 'We probably should have asked for paramedics.' Demonstrators block Martin Luther King Boulevard as they marched through Baltimore on Thursday . Police said one man was arrested for assault, and another for destruction of property during the noisy march from City Hall to the Western District police station . Making a point: Captain Erik Pecha is pictured talking with a young demonstrator outside the police headquarters . The Southern Christian Leadership Conference said it wouldinvestigate Gray's death, and the local head of the civil rightsgroup said it lacked confidence in a police probe .
An attorney for at least one of the officers, Michael Davey, said Thursday that Gray was not strapped in during transport.
The 25-year-old was cuffed at the wrists and shackled at the ankles - he was found to have a fatal spine injury, but the cause remains unknown.
'Nickel rides'  have caused spinal injuries in the past. Another Baltimore man, Dondi Johnson, was killed by such a ride in 2005.
Department rules were updated nine days before Gray's arrest stating that all detainees shall be strapped in by seat belts or other device.