US helicopter crash kills key Zimbabwe opposition leader Roy Bennett and his wife were killed in a helicopter crash in New Mexico.

 -- A key Zimbabwe opposition leader was killed Wednesday night in a helicopter crash in the United States, authorities said.

Roy Bennett, an outspoken critic of longtime Zimbabwean President Robert Mugabe, who was forced to resign in late November, died when a helicopter crashed in a remote area of northeastern New Mexico, according to the New Mexico State Police.

Bennett, 60, had left Zimbabwe under Mugabe's rule for exile in South Africa, but continued to be a fierce opponent of the president. He was listed by New Mexico State Police as a resident of Colorado and South Africa. It's unclear why he was in New Mexico.

His wife, 55-year-old Heather Bennett, also died in the crash, along with the pilot, the co-pilot and 61-year-old Texas investor Charles Ryland Burnett, police said.

One unidentified passenger who sustained serious injuries in the crash was expected to survive, police said. The survivor called 911 to report the incident around 6 p.m. local time Wednesday, but the exact location of the crash was uncertain.

Authorities searching for the crash site spotted wreckage on a rancher's property east of Raton, where a grass fire believed to have been caused by the downed helicopter had burned approximately a 1-mile radius around the crash, according to police.

Apart from the survivor who dialed 911, first responders found two men alive but in critical condition. One of them died at the scene a short time later, and the other succumbed to injuries while being airlifted to a hospital. The three other people aboard the downed helicopter were found dead at the scene upon arrival, police said.

The limited flight data available indicated the privately-owned Huey Bell UH-1 helicopter was traveling from Raton to Folsom, police said. But the nature of the flight and the cause of the crash is unknown. The Federal Aviation Administration is investigating.

Bennett, who was born in Zimbabwe, was a founding member of the Zimbabwean opposition party, Movement for Democratic Change. He had previously been a commercial farmer in the mountainous Chimanimani region, according to party spokesman Obert Chaurura Gutu.

Although he was white, Bennett was known among many black Zimbabweans as "Pachedu," which means "one of us" in Zimbabwe's Shona language. Bennett spoke the native language fluently, Gutu said.

"His work with the local farming communities in Chimanimani district is very well-documented and he was also a renowned philanthropist who assisted hundreds of local villagers with school fees for their children and other necessary requirements to look after their families," Gutu said in a statement released to the media Friday.