People comforted one another after a shooting was reported on the Florida State University campus in Tallahassee on Thursday.Credit…Kate Payne/Associated Press

A student who was in the student union at Florida State University, near the scene of the shooting, said he was momentarily confused by the sound of gunfire but quickly took cover.

“I’m still pretty disoriented from it,” said Victor Castillo, 20, a sophomore studying business management. He had been eating lunch in the building when he heard what sounded like explosions, then hid under his stool.

“All of a sudden, I hear boom, boom, boom,” Mr. Castillo said. “My ears started ringing; I didn’t know what was going on. I didn’t think it would happen here.”

Mr. Castillo sheltered in place until the police evacuated the building.

Chris Coutts, 51, a professor of urban planning at the school, said he was “baffled” by what had happened. “This is the second one since I’ve been here,” he said as he walked to his car after having sheltered in place. He was referring to a 2014 shooting in which a gunman wounded three people in the university library.