The manslaughter trial is underway for the driver of a pickup truck that slammed into a Honolulu police officer’s patrol car — igniting it in flames and claiming the officer’s life as he tried to assist a stranded H-1 freeway motorist in 2012.

A witness who tried to save HPD officer Garret Davis, 28, described trying to pull him from his burning patrol car on Jan. 21, 2012.

The car had been rear-ended by a pickup truck near the Kaonohi Street overpass, and Davis was pronounced dead at the scene.

Davis had stopped his patrol car and turned on its flashing blue lights in the left, eastbound lane of the freeway to protect a stalled vehicle with a blown tire from oncoming traffic.

The truck driver, Scott Frederick Ebert, 45, of Mililani, is on trial for manslaughter in state court.

Joseph Collinge testified Monday that he was heading into Honolulu on his motorcycle on the H-2 freeway when a large pickup truck with raised suspension and large tires sped past him at what he estimated was 100 mph.

“Fast enough that when I was going 70 mph, I could feel the force of the air it was pushing as it went by me,” he said.

Collinge said that the next time he saw the truck, it was at the scene of the fiery crash.

Patricia Poston testified that she was driving her sport utility vehicle on the freeway just before the Kaonohi overpass when the pickup truck passed her going 75-80 mph. She said she also noticed the flashing blue lights of the police car ahead. Seconds later, Poston said, she saw the truck crash into the back of the police car.

“I didn’t see any brake lights or lane change of the truck,” she said.

Her husband, Eric Poston, said he felt their SUV move sideways slightly and heard his wife comment about a speeding motorist but did not see the truck pass them because he was looking at his telephone. He said he looked up when he heard an explosion and his wife scream.

“And I see this car up in the air, 10 feet up in the air, in flames, and I knew it was a real bad accident,” he said.

Poston, who is a Navy corpsman, a job similar to an Army medic, said he ran out of the SUV toward the burning car, which had turned around facing oncoming traffic. He said the car’s driver door was open, and Davis was unconscious and lying across the front seat.

Because the heat of the fire was coming from the back of the car, Poston said he tried pulling Davis out from the front. He said Davis didn’t move because the car’s windshield had collapsed on top of him. Poston said he had to space his efforts because of the heat and explosions of bullets inside the car. He said he had to stop when the flames spread to the front seat, then engulfed the entire vehicle.

Davis’ sister is suing the federal government over her brother’s death. Ebert was heading to Honolulu Airport to attend Air Force Reserve training on the mainland when his truck hit Davis’ patrol car.

A member of Ebert’s reserve unit testified that Ebert was supposed to be at the airport at 8 p.m. for a commercial flight that was scheduled to depart at 10 p.m.

The city says its Emergency Medical Services received its first 911 call about the crash at 8:19 p.m.