Police said the chopper came down near the Campo Felice resort during a mission to evacuate an injured skier.
"The area where it came down is hard to access at the best of times, and thick fog is making it even more difficult," a police spokesman told AFP.
"Several teams are trying to get there."
The helicopter issued a crash signal and the police had received reports of a loud explosion being heard, the spokesman said.
Campo Felice is located close to the epicentres of recent earthquakes and last week's deadly avalanche.
The map below shows the location of the resort, in Rocca di Cambio, south of L'Aquila and the Gran Sasso National Park where the avalanche-hit Hotel Rigopiano is located.
The accident happened as firefighters, mountain police and other emergency services are grappling with the aftermath of the earthquakes, the heaviest snowfalls experienced in decades and the avalanche that swamped the Hotel Rigopiano last week.
The Rigopiano is located on the other side of Monte Gran Sasso, the near 3,000-metre peak that dominates the area.