Central High School in Carrollton, Georgia

CARROLLTON, Georgia (CNN) -- A 15-year-old girl was killed and her 17-year-old boyfriend was critically wounded Friday in what authorities consider a suicide pact shooting at a local high school.

The double shooting took place at Central High School 15 minutes after class began. The girl died later at Tanner Medical Center in Carrollton, according to authorities.

The boy had a bullet wound to his head and was taken 50 miles by helicopter to Crawford Long Hospital in Atlanta. Neurosurgeons there decided against immediate surgery. His prognosis remains uncertain.

The couple was discovered in the girls' restroom in the school's science wing by a school employee. According to police, a 22-caliber pistol, taken by the girl from her parents' safe, was used in the shooting.

"We do know each of them intended on dying today," Sheriff Tony Reeves said.

Investigators said they believed the boy killed his girlfriend and then turned the gun on himself. The gun was found near the boy's body.

The boyfriend had talked darkly in recent days, telling other students "he probably wouldn't be here much longer," recalled Tiffany Osteen, 17. No one took the talk seriously. "He likes to get attention," she said.

The teen-agers had been forbidden to see each other by the girl's parents, said schoolmate Alexis Smith, 15. She also said the girl told friends she and the boy might commit suicide rather than end their relationship.

Friends described the girl, who played clarinet in the school marching band, as smart and friendly, while her older boyfriend was more of a loner.

"He was funny, but he didn't really have any friends," said Osteen. "He was strange."

Some students said they had heard that the girl's parents didn't approve of her relationship and that she had been under pressure to stop seeing the boy.

Scott Cowart, principal of the school with an enrollment of about 1,000, declined to discuss the couple. He said the school was focusing on helping students cope with their shock and grief.

"Everybody was scared and shocked," said student Michelle Crews, 14. "A lot of people were crying."

Cars quickly lined both sides of the street in front of the school as parents, panicked as word spread of the shooting in this town of 17,000, raced to pick up their children.

"They said all the color went out of me; I got weak in the knees," said Joani Osteen. "You see it on TV all the time, but not here."

News helicopters circled overhead and television satellite trucks set up in the Baptist church across the street from the brick school buildings.