WEST LAFAYETTE, Ind. - Police say the man killed in a Purdue University shooting was a senior at the school who was a teaching assistant, and the suspect is also a student.

Purdue Police Chief John Cox said Tuesday that 23-year-old Cody Cousins of Warsaw, Ind., is being held in the Tippecanoe County Jail on a preliminary charge of murder.

Cousins is accused of shooting 21-year-old Andrew Boldt of West Bend, Wis., in the university's Electrical Engineering Building around noon Tuesday.

Cox says police are still investigating the motive behind the shooting but that it appears Cousins targeted Boldt. No one else was injured.

Cox says Boldt was a senior and worked as a teaching assistant in the school. Cousins is a student in the engineering school.

Shortly after the report of a shooting came in, Purdue officials issued a text alert telling those on the campus about 60 miles northwest of Indianapolis to seek shelter. Within two hours, the university said there was no ongoing threat on campus and allowed normal operations to resume in all buildings except Electrical Engineering.

Television footage showed a fire truck and several law enforcement vehicles around the building. Photographs from the scene showed police officers with guns drawn and a person in handcuffs being led away.

Students described a chaotic scene when the first report came in.

Julissa Martinez, a freshman nursing student from Portage, said she was in psychology class on another part of campus when she received the text message saying the university was on lockdown. She said her professor briefly kept teaching, then stopped lecturing so that students could contact people to let them know they were safe.

"He tried to get everything under control because people were freaking out," she said.

She said students were nervous because there was a lot of speculation about the severity of the situation.

"It was scary because you hear about it, but you never expect it to happen on your campus," Martinez said.

Senior Saran Mishra, editor of the Purdue Exponent, the campus newspaper, said some students reported hearing fire alarms and were told to evacuate.

"Right now I'm still in shock," he said.