OTISFIELD — Three boys were sent to the hospital Thursday – one by LifeFlight helicopter – after two motorboats carrying a total of 10 people collided on Thompson Lake in Oxford County.

Lt. Adam Gormely of the Maine Warden Service said a water-ski boat driven by Matthew Nolan, 58, of Potomac, Maryland, collided around noon with an open-bow boat driven by Ken Bartow, 60, of Biddeford, who was with his grandson and the boy’s friend.

Bartow and the boys were thrown into the water. One of Nolan’s passengers also ended up in the water.

Two of the injured boys were taken to the hospital by ambulance, while the friend of Bartow’s grandson was taken to Maine Medical Center in Portland by LifeFlight helicopter. Their names or conditions were not available Thursday night, but Gormely said the boy at Maine Medical Center is 9 years old and from Massachusetts.

Gormely said Nolan’s boat, towing a water skier, was heading away from the shore when it collided with Bartow’s boat a few hundred yards off shore.

After the crash, Gormely said, Bartow’s empty boat, which was still running, spun around and headed toward shore, where it ran aground.

The injured boys were pulled out of the water by Harold Kowal, a retired attorney who lives on the lake. His wife, Ruth, saw the accident from their yard.

“It was a huge crash. It was like a car crash,” she said Thursday night. “I yelled to Harold, ‘There are people in the water, you have to get out there.'”

Harold Kowal told his wife to call 911 and got in his speedboat.

He said a visitor at the cabin next door yelled out that he was a paramedic and would go out with Kowal.

Kowal said they found five people, including the water skier, hanging on to a 3-foot-long boat cushion. Kowal and the paramedic lifted some of them into Kowal’s boat by their life jackets. Others got onboard by themselves.

“It was perfectly obvious one of the boys was in the worst condition,” Kowal said, with “blood pooling in his right ear.”

He said the paramedic, named Chris, called 911 twice from the boat and said they needed LifeFlight.

“The warden said I saved lives,” Kowal said Thursday night, “but it’s Chris who saved that little boy’s life by calling for the medevac.”

Another one of the boys, he said, couldn’t move his left leg and was in considerable pain.

Kowal knew he had to act quickly as soon he heard the crash. “I just started moving,” he said. “I looked, I knew what I had to do and I went.”

Kowal said that as he was going out to pick up the boys, Nolan and his remaining passengers were returning slowly to shore in the ski boat, which had a gaping hole in the left front.

The accident is under investigation, but Gormely said alcohol doesn’t appear to be a factor.

“I don’t know what they did wrong. Maybe no one did anything wrong,” Gormely said.

He said it was one of the most serious boat accidents he has seen.