A medical helicopter crashed into a farm field in southeastern Indiana shortly after takeoff Sunday, killing all three people aboard.

The Air Evac Lifeteam aircraft crashed about 1:17 p.m. near Burney in rural Decatur County, about 40 miles southeast of Indianapolis, authorities said.

Indianapolis television stations showed video of the wreckage in a field. Witnesses told investigators that the helicopter's nose tipped down, the aircraft went down and exploded.

"The helicopter exploded on impact and instantly burst into flames," Decatur County Sheriff Daryl Templeton said. "There's just not a whole lot left."

The Decatur County coroner was working Sunday to identify those killed in the crash.

"This is a tragic day for us here at Air Evac Lifeteam," Air Evac Lifeteam President Seth Myers said in a prepared statement. "These were our family members and we are devastated at this loss. Our focus at this time is on providing support for the family and friends of these crew members."

The company said the crew included pilot Roger Warren, flight nurse Sandra Pearson, and flight paramedic and base manager Wade Weston. There were no patients on board.

Media reports said the helicopter had been at a fundraiser for the Burney Volunteer Fire Department and crashed as it was returning to base at a hospital in Rushville.

The cause of the crash was not immediately known. The FAA said the investigation could take months.

Officials from the National Transportation Safety Board were expected at the site Monday.

Air Evac said its bases in Indiana were not accepting patient missions until crews, many of whom had flown with those killed, could be assessed.

"They will go back into operation when it is determined they are ready," the company said.

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