A 32-year-old and a 36-year-old accidentally started a forest fire in the southern German state of Bavaria while trying to signal for help, local police said on Monday.
The two men were hiking on the Jochberg mountain to celebrate New Year's Eve when the younger man fell almost 100 meters (328 feet) and broke his leg shortly after midnight on Sunday.
The hikers then lit a fire to possibly attract attention, and the flames got out of control. The fire quickly spread, covering 100 hectares (247 acres) of the mountain.
On Monday, officials indicated that it was unclear whether the men started the fire before or after the younger man fell.
"According to the evidence so far, we assume that the two men made a campfire. Whether this happened before or after the one hiker's fall is still being investigated," police spokesman Anton Huber told Bavarian public broadcaster Bayerischer Rundfunk.
Huber added that mountain rescue services were notified about the hiker's accident by an emergency call made from one of the men's cellphones.
Over 100 firefighters worked through the night to battle the blaze, while seven helicopters picked up water from two nearby lakes.
Some local roads have reopened, but authorities said it could take days to fully extinguish the fire.
Police and the public prosecutor's office are investigating the possibility of negligent arson, Bayerischer Rundfunk reported.
rs/kms (dpa, Bayerischer Rundfunk)