Investigators were combing through debris scattered across a field in northwest Oregon Thursday after two helicopters collided midair, killing three people and forcing the closure of a nearby highway, officials said.

Texas flight instructor Maddie Aasbo, 22, and Oregon pilot Tyler Sturdevant, 38, died in the crash as well as a student pilot from the United Kingdom, Yamhill County Sheriff Sam Elliott said during a news conference.

Aasbo was in one helicopter with the student pilot and Sturdevant was the sole occupant of the other, the sheriff said.

The aircraft crashed to the ground in a private farm field near McMinnville Municipal Airport, officials said, with a red helicopter left crumpled in pieces and a green helicopter lying upside down. McMinnville is about 40 miles southwest of Portland.

A one-mile stretch of nearby Highway 233 was closed due to the crash, the Oregon Department of Transportation said Thursday afternoon, giving no estimate for reopening.

A green helicopter was seen lying upside down in a field after a deadly helicopter collision in McMinnville, Oregon, on Thursday.

Leo Rodriguez said he called 911 after witnessing the crash from his family vineyard.

“All of a sudden I hear this big boom and this metal breaking, and I look up and just see these two helicopters just collided in mid-air,” he told CNN affiliate KPTV.

“It took me a while, for my brain to figure out what I was seeing. You don’t see this every day. They twisted and fell to the ground.”

The sheriff’s office asked the public to avoid the area and have “patience as we respond to this critical incident.”

The investigation into the crash, which took place around 2:15 p.m. local time, is being led by the National Transportation Safety Board, according to the FAA, which is also probing the incident. The federal investigators were at the scene Thursday night, the sheriff said.

The two aircraft involved were a Robinson R-22, which was the instructional flight, and an Airbus AS350, which was on a maintenance flight, the NTSB said.

Law enforcement responds to a deadly helicopter collision near McMinnville Municipal Airport on Thursday.

One of the helicopters was operated by Jerry Trimble Helicopters, a helicopter flight training school and rental service for private flights, the company said in a statement.

“Jerry Trimble Helicopters is deeply saddened to confirm that one of our aircraft was involved in an aviation incident this afternoon,” the company said. “Our hearts and thoughts are with the individuals involved, their families, and everyone affected by this event.”

The company added it is cooperating with authorities in the investigation. (CNN)