It was a typical day of class Monday in the Michigan State University Engineering Building for David Grabowski. 

Until about 1 p.m.

The 21-year-old senior from Bloomfield Hills was in class in the 1200 wing of the building, located at the east-most portion of the first floor, when he heard a person screaming in the hallway.

"Of course, we just assumed that someone got into an argument or something and would stop right away," he said. "But then there was more screaming and it wouldn't stop."