The suspected gunman was reportedly in custody.
The slain officer was identified as Martinus Mitchum, 38, according to NOLA.com.
Teams from Carver and Warren Easton high schools were meeting in a playoff game at Carver High School when the suspect tried to enter, FOX 8 of New Orleans reported.
The game was halted following the shooting, NOLA.com reported.
The officer was working as a security officer for the game, WWL-TV reported.
The suspect had been arguing with a school employee and the law enforcement officer attempted to intervene and remove the suspect from the building, according to NOLA.com.
At some point, the suspect pulled out a gun and shot the officer in the chest, the report said.
Multiple shots were fired, according to a photographer from WWL who was at the scene.
The slain officer was a member of the force at Tulane University in the city and also served as a City Court constable, Shaun Ferguson, superintendent of the New Orleans Police Department, told FOX 8.
The shooting remained under investigation, authorities said.
- [LLODO] California mother who tortured, murdered son wants conviction tossed
- [LLODO] Ex-NFL player Phillip Adams reportedly had medication taken away before South Carolina killings
- [LLODO] South Carolina sheriff emotional recalling doctor, family slain by ex-NFL cornerback Phillip Adams
- [LLODO] North Carolina student arrested in connection to murder of his roommate, fellow student
- [LLODO] Connecticut man fatally stabbed his mother, police say
- [LLODO] Texas man pleads guilty in murder-for-hire plot to kill his father
- [LLODO] Pennsylvania missing pregnant woman found dead in Southwest Philadelphia
- [LLODO] Chicago man used ‘samurai knife’ to kill relative, prosecutors say
- [LLODO] Two Maryland shootings leave a total of 4 dead, police say