The shock wave from Monday's natural gas blast rattled homes and buildings in Plymouth and could be heard more than 20 miles away in Oregon.
Some residents watched flames near a 90-foot-tall storage tank shoot 30 feet into the air, sending plumes of black smoke drifting into the morning sky.
Dawn Wellam thought a train had crashed on the tracks near her home on Blue Sky Road, overlooking the plant.
"It was a very loud boom. Just like something blew (up)," Wellam said. "We looked at the train tracks to see if it came from there. We thought it could have been an earthquake."
Ambulances and fire trucks raced toward the plant as neighbors in the small town of about 300 began to file out of their houses for a better look.
Don DuBois stood in the Agate Acres RV Park near the plant, as the smell of natural gas spread through the town and crews worked to put out the flames, he said.
"We thought something blew up in the trailer park," he said. "Then, all you see is this black smoke rising."
Emergency crews walked door to door, notifying residents they had to leave immediately because of the danger of another, larger explosion.
Residents scrambled to gather belongings to toss in their cars and trucks. Some grabbed prepared emergency bags while others fled with just the clothes on their backs.
Officials had no answer for when residents would be allowed back. People were told to leave as quickly as possible and head to the Umatilla County Fairgrounds in Hermiston.
"I went off without my medication," said Sharon Gray, who lives near the plant. "All I grabbed was two blankets, my dogs and some dog food."
About 20 cars lined the fences inside the fairgrounds Monday as neighbors sipped from water bottles and ate lunches provided by the American Red Cross.
The Red Cross set up a shelter at the fairgrounds Monday night and fed those who chose to stay. Residents were not expected to be allowed back into their homes until at least Tuesday.
Some volunteers from the Tri-City chapter of the Red Cross traveled into Oregon to help residents, said Peggy Hoggarth, executive director.
Many residents were shaken after the blast but relieved that the incident wasn't worse, they said.
They are aware of the risks involved with living next to the plant and the potential for a catastrophic explosion, but most said they felt safe continuing to live in the rural farming community.
"They do a good job of maintenance and having safety precautions in place," said Ralph Schrattenholzer, who lives on Christy Road, next to the plant. "At the end of the day (Tuesday's incident) is not as big of a deal as it feels. But the potential is there."
-- Tyler Richardson: 582-1556; email@example.com; Twitter: @Ty_richardson