The discovery was made at about 7:45 a.m. in the 9800 block of Town Park Drive near the West Sam Houston Parkway.
Homicide detectives are on the scene, but at this time the man's cause of death is unknown. The man was found just before the start of the school day at Collins Elementary. Investigators believe the death is unrelated to the campus.
Detectives say the victim was a Hispanic male in his 20s. A passerby reportedly heard gunshots in the area before police discovered the man deceased.
Alief ISD officials issued a statement that read in part, "The safety and security of our students and staff is our highest priority."
No recess or any outside activities will be held today due to the police investigation, school officials said.