Where can I find out more about other people rising from the dead, when Jesus died on the Cross? 51 When Jesus died, the curtain in the Temple was torn into two
  pieces. The tear started at the top and tore all the way to the
  bottom. Also, the earth shook and rocks were broken. 52 The graves
  opened, and many of God’s people who had died were raised from death.
  53 They came out of the graves. And after Jesus was raised from death,
  they went into the holy city, and many people saw them. -Matthew 27:51


Aside from Jesus healing people, this appears to me as the biggest supernatural event in the Gospel: Other people rising from the dead, out of graves!

However, there is only 1 line given to this?

Are there any more details about what happened here?

Thanks!
There is no doubt this truly happened, but in many of the events in the gospels, they are the only records of the history which is why they written. I think when one gospel has something and the others do not, we can assume this is not to be central in our view of the ministry of Christ, but that it is important from the angle that the individual writer takes.**

For example take Alfred Edresheims way of categorizing the gospels (which I like):

Matthew (Jewish view of the Christ) -  has for its main object the Discourses or teaching of the Lord, around which the History groups itself. It is intended as a demonstration, primarily addressed to the Jews, and in a form peculiarly suited to them, that Jesus was the Messiah, the Son of the Living God.

Mark (general view of the Christ) - is a rapid survey of the History of the Christ as such. It deals mainly with the Galilean Ministry. 

Luke (Gentile view of the Christ) -  complements the narratives in the other two Gospels (St. Matthew and St. Mark), and it supplements them by tracing, what is not done otherwise: the Ministry in Peroea. Thus, it also forms a transition to the Fourth Gospel of the Judæan Ministry.

John (the Church’s view of Christ) - which gives the highest, the reflective, view of the Eternal Son as the Word, deals almost exclusively with the Jerusalem Ministry.

With this category of Mathew we could say why did Mathew think the many dead raising to life and the thunder was important along side of the curtain tearing?  We must keep in mind the gospels only select certain highlights of the miracles the Lord did and we can assume those that are recorded are only a drop in the bucket, juts as the words he spoke were much, much more than what was recorded. The words in the gospels are just little snippet summaries.

One possible answer is that Mathew, as writing to a Jewish audience, really wanted to stress the end of the Jewish Law and power in Christ’s death to end it. Besides the Jews expected Messiah to bring about a resurrection of the dead soon after his arrival to this earth (see here). The other three may have not have included it in their limited selection of material, perhaps because they felt the focus should really be on the greater event of Christ’s death. So this is a great miracle and thankfully Mathew recorded it, but we must not let any miracles cloud the greatest event which was Christ’s death.