A medical helicopter crash-landed outside an Oklahoma City nursing home early Friday, killing two people onboard and injuring a third who was pulled from the burning wreckage, officials said.

Only the flight team was onboard when the helicopter crashed while headed from Oklahoma City to Watonga, 112 kilometres away, to pick up a patient, said Fire Department Battalion Chief Marc Woodard. No patients were aboard the aircraft and no one on the ground was seriously injured or killed, he said.

But two men riding in the helicopter, including the pilot, were killed in the crash, said Woodard.

Witnesses say employees from the St. Ann Nursing Home pulled the survivor from the wreckage. That man is in critical condition at an Oklahoma City hospital.

The crash occurred between the St. Ann Retirement Center and the St. Ann Nursing Home, which are operated by the Archdiocese of Oklahoma City. Witnesses said there were two explosions.

"I was awake and I heard this boom and it shook my bed," said Betty Steel, who lives in a retirement village adjacent to the nursing home.

Rachel Njafuh said when she arrived for work at the nursing home, flames and smoke were pouring from the wreckage.

"My colleagues pulled a man from the (helicopter) just before a second explosion," she said.

Sky was clear

Oklahoma City received only a dusting of snow from the large storm system that has been moving eastward through the nation's midsection this week. Woodard said the skies were clear Friday morning when the helicopter crash-landed about 30 metres from the front door of the nursing home in the northwest of the city.

"I think the pilot did a miraculous job landing it where he did," Woodard said. "It's 65 feet [20 metres] from a nursing home on one side and 150 feet [46 metres] from a retirement village on the other."

Federal Aviation Administration investigators were at the scene within hours, combing through the helicopter's charred remains for clues.

One person on the ground suffered minor injuries and was treated at the scene, said Lara O'Leary, a spokeswoman with Emergency Medical Services Authority.

The helicopter belonged to EagleMed LLC, a Kansas-based medical transport company, O'Leary said.

In July 2010, an EagleMed helicopter crashed in a field in Kingfisher, about 50 miles northwest of Oklahoma. The helicopter's pilot and a nurse on board the aircraft were killed in the crash.

On that flight, the EagleMed helicopter was headed from Oklahoma City to pick up a patient at a hospital 145 kiloemtres away. The National Transportation Safety Board has not yet released a probable-cause report from the 2010 crash.