Police have charged 22-year-old Trystan Terrell with two counts of murder and other charges for allegedly shooting and killing two students and wounding four others at the University of North Carolina Charlotte. After the gunfire began around 5:40 p.m. Tuesday , the entire UNC Charlotte campus was put on immediate lockdown.

Sophomore Tristan Field, who told CBS News he was in the classroom where the shooting took place, said the scene turned from confusion to chaos within seconds. Field believes the shooter sat with the other students for about 10 minutes before opening fire, reports CBS News' Chip Reid.

"All of a sudden, without warning, no one yelled, no nothing. This gun started ringing out," Field said.

He said as many as 50 students tried to exit through one of the room's two doors.

"It was absolute panic. A chair fell in front of the door, so people were tripping over that, like, trying to climb over it," Field said. "Some people fell down. It was like water through a funnel, but it wasn't fast enough."

Authorities have not yet identified the two people who were killed. The shooting happened on the last day of classes.

A father at a nearby building captured video of an apparent victim being carried to safety and said he saw the students fleeing.

"They came flying out of the building, were jumping the brick wall, running all different ways," Chris Neal said.

The student newspaper identified one of the four injured as their sports writer, Drew Pescaro, who they say is out of surgery and is in stable condition. Law enforcement was nearby preparing for an on-campus concert and took the suspected shooter into custody before he left the classroom.

"We were able to get to the building and ... our officer immediately went to the suspect to take him down," UNC Charlotte police chief Jeff Baker said.

Among the charges Terrell is facing: two counts of murder and four counts of attempted murder. Officials say they still have not been given a motive for the shooting.

All final exams have been cancelled here through the weekend. The governor is promising reforms to keep guns off the state's campuses and assure that students are safe.