The alleged shooter was also shot dead, Bernama reported.
The incident happened at around 1:10 pm local time (0510 GMT) inside Camp Evangelista in Cagayan de Oro City. The four victims died at the scene, command duty officer Army Major Alden Brinas was quoted as saying in a report.
After the initial shooting, the gunman attempted to enter another room, but two other soldiers wrestled with the attacker, seized his firearm and shot him dead, Brinas said.
The critically wounded soldier was undergoing treatment at a local hospital, according to the officer.
Brinas did not mention what triggered the gunman to run amok. An investigation into the shooting incident is underway.
Army spokesperson Major Francisco Garello said the military was conducting its internal investigation “to look into all angles that triggered the incident.”