(CNN) One student was killed and another was in critical condition after an accidental shooting during dismissal time at a high school in Birmingham, Alabama, police said.

At least two gunshots were fired, killing a 17-year-old female student and injuring a 17-year-old male student at Huffman High School, said Birmingham police Chief Orlando Wilson. He said police considered the shooting accidental, but did not elaborate.

Huffman was placed on a brief lockdown and police were called to the scene when the shooting occurred. The school has metal detectors, and school resource officers were on site at the time of the shooting, said Birmingham City Schools Superintendent Dr. Lisa Herring. She said Huffman will be open Thursday, and counselors and police will be on campus.

The girl who was killed was about to turn 18, had been accepted into college and had aspirations to be a nurse, Birmingham Mayor Randall Woodfin said.

"Our hearts are heavy," he said.