Moscow ? A Russian transport helicopter jammed with troops crashed Monday in Chechnya, and Russian news agencies said as many as 85 servicemen were killed. Russian officials said they did not know how many were killed or whether the aircraft was shot down by rebels.

Reporting an engine on fire, the pilot wanted to make an emergency landing near Russia’s front-line base for its battle with separatist rebels, one Russian official said.

The Mi-26, described as the world’s largest helicopter, was carrying at least 132 people as it crashed and burned near the Russian military headquarters at Khankala outside Chechnya’s capital of Grozny, said Col. Boris Podoprigora, the deputy commander of Russian troops in Chechnya.

Podoprigora said 32 survivors were hospitalized and doctors were treating other wounded at the scene. Officials said the wreck burned for at least an hour after the crash.

He did not give a death toll.

Earlier, Interfax reported that about 80 servicemen were killed, citing a source at military headquarters. ITAR-Tass, also citing a source there, put the death toll at 85.

Sergei Fridinsky, a deputy prosecutor general, said investigators were examining two possible causes of the crash: The helicopter was shot down by rebels, or it suffered a technical problem.

A high-ranking source at the military headquarters said authorities believed it was more likely a technical problem, but nothing was being ruled out.

Fridinsky said the helicopter fell onto a minefield. Podoprigora could not confirm that, but he said rescuers were working in difficult conditions.