Investigators have found the body of the suspected shooter. They say he appears to have acted alone, before shooting himself dead. His motive is still unclear, but some speculate -- including this professor from DePaul University -- that this may be another ISIL-related attack.

"Certainly it suggests that, given the pattern of scene over the last 6-8 months. The reporters are absolutely right. This is a pattern we saw over attacks..... This is highly suggest about that," said Thomas Mockaitis, professor of history, Deoaul University.