The iconic red helicopters have flown Sonoma County skies for 25 years since a local doctor decided rural residents needed quicker care.

Now REACH choppers are part of the largest air ambulance company in the world.

REACH Medical Holdings announced Wednesday that the company was sold, a deal that was previously reported to be in the works.

The company was sold to Air Medical Group Holdings, a subsidiary of Mitt Romney's old investment firm Bain Capital and will become the company's fourth air ambulance company.

Air Medical is borrowing $245 million to help finance the acquisition, according to Standard & Poor's.

Newly appointed REACH president Sean Russell did not immediately return telephone calls seeking comment about how the acquisition would affect the Santa Rosa company.

REACH, which stands for Redwood Empire Air Care Helicopter, has provided a key link in the chain of emergency response, particularly in rural areas of Sonoma County. The air ambulances fly critically ill or injured people to hospitals.

The company has transported more than 75,000 patients since Santa Rosa Memorial Hospital emergency room physician John McDonald started the helicopter program in 1987.

The company grew to include 18 bases and nearly 400 employees in California, Oregon and Texas.

In a statement, Russell said he looks forward to "getting the scale benefits of being part of a larger air medical provider while staying true to what has made REACH a respected caregiver."

"AMGH has made it clear that our company will continue to maintain its identity, values, culture and commitment to the vision of our founder," Russell said.

The company plans to add a new aircraft to the northern California fleet, an EC-135 helicopter.

Air Medical Group Holdings flies more than 200 helicopters and airplanes in 27 states. It also owns Air Evac Lifeteam of West Plains, Mo., Med-Trans Corp. in Dallas and EagleMed of Wichita, Kan.

You can reach Staff Writer Julie Johnson at 521-5220, or on Twitter @jjpressdem.