FORT LAUDERDALE, Fla. -- A 15-year-old girl was charged with fatally shooting another student during an argument Wednesday at a Fort Lauderdale high school.

Teah Wimberly was charged with first-degree murder and discharging a weapon on school property, Fort Lauderdale Police said in a news release. The body of sophomore Amanda Collette, also 15, was found on a hallway floor at Dillard High School around 11 a.m. She was shot in the torso while students were changing classes.

"This is a situation where we are more than heartbroken," said Jim Notter, the superintendent of schools for Broward County.

Wimberly left campus and walked across the street to a restaurant called Captain Crab's Take-Away where she called authorities and told them that "she had shot her friend," said Sgt. Frank Sousa, a police spokesman. Authorities took her into custody at the restaurant and recovered a gun.

Messages left with police seeking an attorney for Wimberly were not immediately returned.

The discovery of the body started a confusing series of events. Police said they did not believe anyone heard gunshots, and an initial examination found no major wound on the girl's body, leading to questions about whether or not she was shot.

Authorities later confirmed the shooting and Sousa said it was possible a smaller-caliber gun was used and the wound closed around the bullet.

Police said no other students were believed to have been involved and the motive was still being investigated.

"This appears to be an isolated incident," Sousa said.

Stephan Willis, a sophomore who said he witnessed the shooting, said the girls were arguing in an outside corridor when Wimberly suddenly produced a gun and shot Collette.

"She's a nice girl. She's quiet. She just keeps to herself," Willis said of Collette. He said he had known the victim since elementary school.

Another student, 14-year-old freshman Hermond Davis, said the outside hallway was crowded after Collette collapsed and students screamed and panicked.

"As I am walking to the cafeteria, I saw this girl collapsed," Davis said. "She just fell, she just fell right out of the sky."

The school was locked down for a short time, but classes soon resumed. Still, as police were announcing the fatality, gates were chain-locked and access was being restricted. Several dozen parents had gathered outside after finding out about the shooting, some openly weeping.

"I'm just trying to get my baby out of here," said Betty Barnes, whose 15-year-old daughter, Tiffany, is a sophomore at the school. "I want to make sure she's OK. It's very scary not knowing."

Dillard has about 1,700 students. They don't pass through metal detectors, but officers are stationed on campus and security cameras are placed throughout.