Melissa Alexander and her 2-year-old son were doing of one his favorite activities Wednesday night — watching the traffic zoom by Highway 20 from his bedroom window.

That’s when the Oak Harbor woman saw a state trooper heading north in an SUV flip on his lights and attempt to make a U-turn at the intersection of Highway 20 and Whidbey Avenue.

A couple driving a truck heading the other direction slammed into the trooper’s Ford Explorer.

From Alexander’s vantage point, it appeared the trooper didn’t see the truck.

Alexander said she had a clear view of the scene from her second story apartment near the intersection.

“The trooper just turned his lights on and didn’t even slow down in the intersection,” she said. “It was like he was the only car out and about.”

Then, once emergency vehicles started to arrive, she watched two more troopers show up and do the same maneuver, “but luckily others were able to stop in time.”

She said she walked down to the scene and tried to give the officers a statement, but they didn’t want it.

“They told us to head home — we were not on the road,” she said.

The 21-year-old trooper and the elderly couple in the truck were all injured, and traffic was snarled for hours.

A state patrol memo of the collision makes no mention of the trooper attempting to flip around. It says the truck struck the trooper’s Ford Explorer as he made a left turn onto Whidbey Avenue.

Drugs or alcohol were not involved. The state patrol’s memo doesn’t indicate a cause.

Oak Harbor Police were on scene, but it’s the state patrol who are the traffic experts, the ones local police consult with to investigate traffic collisions, said Oak Harbor Police Chief Ed Green. Even though a trooper is involved, the state patrol would still handle the investigation on Highway 20 unless there were some reason they didn’t have the staff to handle it, he said.

However, there are enough troopers who work in this region “there is a good chance troopers not known or assigned to Whidbey Island were brought in to handle the investigation,” he said.

A detective with the state patrol is handling the investigation of this incident because it involved a trooper, said Heather Axtman, a spokeswoman with the Washington State Patrol.

The investigation to determine the cause may take several weeks.

Axtman said she was surprised Alexander said she was turned away. She’s worked crash investigations.

“It’s get a witness statement from anyone you can,” she said.