Police are asking the public for help as they try to find the shooter who opened fire and hit four vehicles driving on State Route 509 near Seattle-Tacoma International Airport.

All of the drivers escaped without injury, local TV station KCPQ reported.

The shootings took place as the vehicles were going southbound on SR 509 at about 1:30 p.m. Wednesday. SR 509 was closed down between 160th and 188th streets for hours while police scoured the area on the ground and from the air for the shooter.

No one was found, but evidence was collected and the highway was reopened by 7:30 p.m.

The State Patrol requested that any witnesses contact them if they were on SR 509 before 2 p.m. Wednesday and saw someone or a group of people walking along the road near Sea-Tac Airport.

“I think I’m in shock a little bit,” Mary Ertl, whose car had a bullet hole in her windshield, told KCPQ.

“All of a sudden something hit my car and it was a big boom and then I realized what it was,” said Ertl.

The bullet exited through her passenger window.

“It just went everywhere. I don’t know, my whole car was just full of dust and glass,” said Ertl.

She got off the highway and pulled over into a lot off 188th Street to call police Soon, she was joined by Mike Luiz.

“It sounded like you ran over a rock, a big rock, but there was a big bounce to the car like something bounced up and hit the car, it was loud,” said Luiz.

When he pulled over next to Ertl, he saw a bullet hole through his door; the bullet stuck somewhere in his seat cushion. Then, another vehicle was hit. A red pickup truck had a bullet hole in the bed.

None of the victims saw anything suspicious.

“Everyone was nonchalant around me, the other cars, it could’ve been anybody,” said Luiz.

A total of four cars were all hit by bullets from an unknown shooter, who police believe had fired from the treeline.

That’s why law enforcement agencies from across the area joined forces to search for the person or people responsible, by air and by foot, with rifles out ready as they tried to find whoever fired the shots.

They shut down SR 509 in both directions for five hours. Even Sea-Tac Airport closed a runway, but no flights were delayed or canceled, according to the airport.

State Patrol troopers don’t believe this was a drive-by shooting.

“We’re looking for an individual from the treeline area. We don’t believe the shots were fired from another a vehicle,” said Trooper Rick Johnson.

All the cars were going southbound and were hit on the driver’s side, just like a black Jeep that was hit near the driver’s window.

So State Patrol troopers searched the brush along the highway for people and shell casings.

“In my recollection, I can’t remember anything like this,” Johnson said.

The victims didn’t know each other so the shooting appeared to be random; there are plenty of questions left unanswered.

For Ertl, she’s just happy to be alive and headed home.

“We’re all still standing. We’re still alive,” said Ertl.