(CNN) Two of 12 Roswell firefighters hurt by an explosion while packaging fireworks for a Fourth of July celebration suffered life-threatening injuries, New Mexico State Police said.

The noon incident occurred in a fireworks storage area at Roswell International Air Center, just south of the city, said police Capt. Lance Bateman.

Two firefighters were transported to hospitals, one with serious and the other with critical injuries, according to Bateman. Ten others were treated on scene for minor injuries.

The fire was mostly extinguished, but the Roswell Fire Department remained on the scene, putting water on hot spots, Bateman said.

Officials are investigating the cause but the blast appears to be accidental, Bateman told reporters.

Read More