SEATTLE - A woman was killed and three people were injured Saturday night when two boats collided on Lake Washington.

Investigators said a motorboat struck a sailboat from behind about 8:30 p.m. and went flying up over the sailboat.

A 37-year-old woman who was on the sailboat suffered severe head injuries in the crash and died after being brought to shore.

"It went up over the top of the back, apparently they could see it coming and tried to get (the boat) to stop -- hit the woman, she was thrown from the sailboat and may have been struck again by the speedboat," said Seattle Police Captain Neil Low.

A 45-year-old man on the sailboat suffered non-life-threatening back injuries, and was taken to Harborview Medical Center, Seattle fire officials said. A third person on the sailboat was unharmed.

A 17-year-old boy who was driving the motorboat and a 16-year-old female passenger were taken to Harborview.

Police are still trying to sort out exactly what led up to the collision.