ELBA (AP) — A medical helicopter pilot and flight instructor were killed in a crash Tuesday during a training flight in western New York, according to state police and the transport company.

The Mercy Flight helicopter went down at around 1 p.m. near the Genesee County town of Elba, which is located about halfway between Buffalo and Rochester, said Maj. Eugene Staniszewski at a news conference.

No patients were on board, authorities said. Mercy Flight said the cause of the accident had not been determined, and that the crash occurred during an annual Bell Helicopter factory training.

Buffalo-based Mercy Flight identified the pilot as James Sauer, a retired New York State Police pilot. The flight instructor, who worked for the helicopter manufacturer, was identified by state police as Stewart Dietrick, of Texas.

A photo from the website of the The Daily News in nearby Batavia showed smoke rising from wreckage in a field.

Staniszewski, of the state police, said the Federal Aviation Administration and National Transportation Safety Board would investigate the cause of the accident. Weather did not appear to be a factor.

Downed power lines were visible near the wreckage but are not believed to have contributed, Staniszewski said.

“I don’t believe the lines caused the crash but the aircraft may have struck the lines on the way down,” he said.

Mercy Flight transports patients to area hospitals in a Bell 429 helicopter, according to the not-for-profit company’s website. The twin-engine aircraft was housed at the Genesee County Airport, which is a little less than 3 miles (5 kilometers) from the crash site.

The company called it an “unspeakable tragedy.”

“This is a very dark day for the Mercy Flight family, we are so grateful for the expressions of love, concern and support expressed by many,” said company president Margaret Ferrentino.

Mercy Flight said it temporarily suspended operations to let their employees grieve and ensure other helicopters could be safely operated. The company said any requests it receives in the meantime will be routed to other local resources.