Position of 了in 发生了什么事 vs 发生什么事了 Compare the position of 了 in the following sentences:

发生了什么事？
What happened?

我想知道他发生什么事了。
I wonder what has happened to her.


Can you explain what the difference is in the positions of the 了?
发生了什么事 VS 发生什么事了


There isn't essential difference between them. They mean the same and are interchangeable.