GLENDALE, Ariz. --Two 15-year-old girls died Friday in a shooting at an Arizona high school that initially caused panic among parents who could not reach their children but later emerged as a murder-suicide.

Police announced that a suicide note was found at the shooting scene near the cafeteria area of Independence High School in Glendale. They said the girls each were shot once, were declared dead at the scene and a weapon was found near the bodies.

"Information gathered by detectives reveal the two girls were very close friends, appeared to also be in a relationship," Glendale police spokeswoman Tracey Breeden said in a statement Friday afternoon.

Breeden said it is believed nobody witnessed the shooting.

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Both teens have been identified, but Breeden said "their names will not be confirmed or released at this time by the police department due to their juvenile status."

Friends told CBS affiliate KPHO the girls were Dorothy Dutiel and May Kieu, both tenth graders at the school.

Police responded to the call of a shooting at Independence High School just before 8 a.m. and found the two victims' bodies on an outdoor portion of the campus under a covered patio near the school's cafeteria, Breeden said.

Officers arrived within two minutes of being called, and the school of more than 2,000 students went on lockdown, Breeden said.There were no threats made to the school or any students or staff there, she said.

One student told KPHO during a phone call that students were heading to class at the time of the gunfire.

"Me and my friend were in front of the school and we heard like, two loud shots, and we thought it was just someone popping a bag or something," the student said. "We didn't know what it was, and then the bell rang and we went to class."

Cheryl Rice said she went to a store after a friend called about the shooting and asked after Rice's 15-year-old daughter. But the girl called as Rice arrived at the store.

Students walk to their parents after being released from lockdown, Friday, Feb. 12, 2016, in Glendale, Ariz., after two students were shot and killed at Independence High School in the Phoenix suburb. The danger at the campus was over, police said, as worried parents crowded stores nearby to meet their children. (AP Photo/Matt York) Matt York, AP

"She said, 'I'm OK,' so I of course started crying," Rice said.

She said it was horrible waiting for word about her child.

"You don't know if it's your daughter or not. You don't know who's being bullied. You don't know who is being picked on. You don't know anything. It could be anybody," Rice said.

School district officials said parents were bused to the school to be reunited with their children. Other students who got permission from their parents left campus on their own.

We are investigating a double shooting at Independance HS. The incident was isolated. The school and neighborhood are safe. — Glendale Police (@GlendaleAZPD) February 12, 2016

Glendale Union High School District alerted parents to the shooting through emails and automatic phone calls and released information on social media, Superintendent Brian Capistran said.

Students typically are not allowed to use their cellphones during lockdowns, but as calls from parents flooded the district, officials asked teachers to have students call family, Capistran said.

Social workers and counselors will be available to students and staff when school resumes Tuesday, the superintendent said.