WINTHROP – Federal investigators were seeking the cause of the weekend crash of a single engine plane that took the life of its pilot.

Marc McDonnell, 51, of Winthrop was alone in the Cessna 172 when it went down at around 9:20 a.m. Saturday in a field near Old Lewiston Road in Winthrop, about 11 miles west of Augusta, police said.

McDonnell was pronounced dead at the site of the crash. No one on the ground was injured.

“According to witnesses on the ground, [McDonnell] banked to steer away from a house,” said Winthrop Police Department Capt. Ryan Frost.

Weather was apparently not a factor, but the cause of the crash wasn’t immediately known. The Federal Aviation Administration and the National Transportation Safety Board were investigating.

The pilot was not in contact with air traffic control and did not file a flight plan, FAA spokeswoman Holly Baker said.

Frost said McDonnell apparently took off from an airfield in Livermore Falls shortly before the crash, but Frost did not know where he was headed.

In another Saturday morning accident in central Maine, the operator of an ultralight aircraft was seriously injured in a crash in Benton.

Gary Seiders, 49, of Sidney suffered multiple injuries, including significant internal injuries, and was transported to Central Maine Medical Center in Lewiston, said Stephen McCausland, spokesman for the state Department of Public Safety.

A woman in the critical care unit Sunday said she could not confirm or deny that Seiders was in the hospital.

The crash took place at Gowers Airfield on Route 139.

“The aircraft was 200 feet up when the engine quit and it crashed, nose first, into a field at the end of the runway,” McCausland said. “There was gasoline in it, so it did not run out of gas.”

The FAA does not investigate crashes of ultralight aircraft, which are not required to be registered with the agency, McCausland said.