Twenty-two Marines were injured Thursday in an accident during training at the Marine Corps base at 29Palms in the High Desert of San Bernardino County.
The Marines were in an amphibious assault vehicle when a fire extinguisher system "inadvertently discharged," the Marines said.
Those requiring medical attention for problems caused by inhaling the halon gas in the extinguisher were treated at base medical facilities and are in stable condition.
By early Friday afternoon, the five Marines who had been kept overnight at the base hospital were released.
The Marines are part of the 2nd Battalion, 3rd Regiment from Hawaii.
Marines and sailors at the sprawling base in the Mojave Desert, the Marine Corps Air Ground Combat Center, train in realistic settings for forward deployments.
Battalions from 29Palms made multiple deployments to Iraq and Afghanistan, and a unit from the base is currently in the Middle East as a crisis-response force.
Battalions from other Marine bases come to 29Palms for training. The base allows for large-scale live-fire exercises, along with the use of tanks and aircraft.