The injured firefighter, who has not been publicly identified, was initially listed in critical condition after the blast. He was later upgraded to stable condition and released from the hospital, officials said.
Crews were called shortly after 1:30 p.m. Monday to a homeless encampment in the 15700 block of West Burbank Boulevard near the Sepulveda Basin Recreation Area, where a grass fire had ignited.
Moments after first responders evacuated the area, a device near the encampment exploded, according to the Los Angeles Fire Department. Crews on the scene halted the spread of the brush fire in about 30 minutes.
An apparent grenade was found at the scene, the Los Angeles Police Department said, and an LAPD bomb squad was sent to the area to investigate.
LAFD firefighter hospitalized after explosion at homeless encampment in Sepulveda Basin
The injured firefighter was transported to Northridge Hospital after he suffered severe burns to his face and ear, the LAFD said.
The firefighter was seen walking unassisted to a waiting helicopter before being airlifted to the hospital.
Ten other firefighters were evaluated for minor injuries.
Firefighters continued to douse flames from the fire hours after the explosion.
On Tuesday, the cause of the fire remained under investigation by the LAPD bomb squad and the LAFD's Arson Division.