Lyons, Colo. ? An air tanker crashed Thursday while working to control a 1,200-acre wildfire burning near Rocky Mountain National Park, killing the two people on board, aviation officials said.

Fire information officer Martha Moran said the plane went down about a mile north of the blaze, which has forced residents to flee about 120 homes in the northern Colorado foothills.

Investigators from the National Transportation Safety Board were en route to where the PB4Y air tanker crashed, about 45 miles northwest of Denver.

Roy Safstrom, who was taking pictures of the fire, said he saw the plane crash.

“There was a bright flash of flame on the left wing. The wing came off and after that he spiraled down,” Safstrom said.

Firefighting air tankers nationwide were grounded for 48 hours while the accident was investigated, Forest Service spokeswoman Terri Gates said.

In June, the nation’s C-130A tankers were grounded after the wings on one of the firefighting tankers snapped off in the air, sending the fuselage to the ground in a fireball in Walker, Calif. Three men were killed.

Hawkins & Powers Aviation Inc. of Greybull, Wyo., owned the C-130A involved in the California crash and the PB4Y model that went down Thursday.

Ryan Powers, operations assistant for Hawkins & Powers, said he had few details about the crash. He said that in addition to the air tanker that crashed, there are four PB4Y planes used to fight fires around the nation.

The names of the victims were being withheld pending notification of the family.