The police officer, who was not identified, was a Tulane police officer and a reserve officer for the Second City Court, said New Orleans police spokesman Shaun Ferguson.
The officer was during a basketball game at George Washington Carver High School when an individual tried to enter and started an altercation with a staff member, Ferguson said.
The officer heard the disturbance and tried to remove the individual from the school. When they got close to the front door, the individual pulled out his weapon and fired a shot that hit the officer in the chest.
The officer was taken to University Medical Center New Orleans where he later died.
According to police, someone is believed to be responsible, Ferguson said, but no further information has been provided about the suspect or a possible motive.