<p>In this aerial photo, the Williams Northwest Pipeline plant is seen after a natural gas pipeline ruptured at the plant in Plymouth, Wash., Monday, March 31, 2014. Benton County Sheriff Steven Keane said some gas leaked from the tank to the ground in a containment area and evaporated into the air, but it was only a small amount. (AP Photo/The Tri-City Herald, Sarah Gordon)</p>

Residents of Plymouth, Wash. woke up Monday morning to a ground-shaking explosion at a liquefied natural gas plant just a couple miles outside of the small town. The blast injured five workers and forced an entire community to leave their homes for the day.

The explosion also punctured one of two large storage tanks at the facility, which began to leak natural gas in a hazy, white cloud. Emergency responders evacuated Plymouth and everything else within a two-mile radius over concern of a second potentially deadly explosion.

A shelter was set up over the river at the Umatilla County Fairgrounds in Hermiston, though the evacuation was eventually lifted in Plymouth after about 11 hours. People living within a mile of the plant were still not allowed back Monday evening as crews continued to assess the safety of the area.

Williams Northwest Pipeline owns the facility, which is set up to store liquefied natural gas. Each storage tank has the capacity to hold 14 million gallons of the material, and were about one-third full when the explosion hit.

A spokesman for the Williams Companies, based in Tulsa, Okla., said they are not yet sure what caused the incident shortly before 8:20 a.m. Neighbors in the area reported feeling their homes rattle and seeing a big fireball flash across the sky.

The victims all workers at the plant are expected to recover. One was taken to Portland after suffering burns, and the others treated for minor injuries at local hospitals. All 14 employees on site at the time are accounted for, according to the company.

Spokesman Tom Droege said safety is their top priority moving forward.

“Right now, we’re focused on coming up with a plan to carry out the investigation,” Droege said. “We also want to be a good neighbor, and are coming up with a plan to assist anybody affected by this and make it less of an inconvenience.”

There was no rupture to the Northwest gas line itself, Droege said, and no customers have been affected.

Because of damage to the south tank, emergency personnel went door-to-door to evacuate Plymouth and closed Highway 14 from Interstate 82 though Paterson for most of the day. No evacuations were ordered on the Oregon side of the river.

Plymouth residents were allowed to go home after 7 p.m. Duane Van Beek, who served as a spokesman for the various emergency response agencies, said the incident was “fairly stabilized” and operations would continue through the night.

Capt. Jeff Ripley with the Benton County Fire District said this is a unique situation that spans multiple jurisdictions. About 120 emergency personnel staged at a truck weigh station near the plant, which is between Umatilla and Irrigon on the north side of the river.

Ripley was very pleased with the level of cooperation between agencies, he said.

“The response has been exceptional,” Ripley said. “Everybody has a piece of this at the moment.”

The Washington State Patrol bomb squad sent in a remote-controlled robot equipped with a camera to survey damage, said Benton County Deputy Sheriff Joe Lusignan. Hazardous material crews then entered later in the afternoon.

Based on all that, they will formulate a plan on what we do next,” Lusignan said. “Lifting the evacuation all depends on the powers that be on scene.”

The plant essentially provides storage for natural gas on the Northwest Pipeline. It is cooled from a gas into liquid state at minus-260 degrees Fahrenheit, where it can be stored in the holding tanks until it is needed farther down the line. The pipeline connects to regional distribution centers across of the Northwest, Droege said.

The facility was immediately shut down and emergency procedures followed after the explosion, according to a Williams Companies statement. Officials will conduct a thorough investigation once it is deemed safe to return to the plant. They believe only natural gas was released, and no harmful vapors are drifting toward residents in the area.

Just across the river in Oregon, Scott Lucas and his wife, Nadine, have a front window view of the plant from their 13-month-old house on the north side of Highway 730. He was looking out when the explosion happened.

The fireball only lasted about 10 seconds, he said. It lit it up. It was crazy.

Lucas said the house has 13-inch concrete walls and triple-pane windows, and he felt the force of the concussion. It was so strong he spilled his coffee, he said.

He also snapped several pictures of the subsequent fire, and said he received a call from the Umatilla County Sheriffs Office to get ready to evacuate. The agency later called back and said to hold off, but Lucas was entirely convinced.

I told my mother to evacuate, he said.

Christian Romero, a worker with Double T Construction of Walla Walla, said he nearby doing some concrete work around the plant when he felt the explosion. It shook the ground, he said, and fires burned while they evacuated within minutes.

“It just blew up,” Romero said. “There was a big old fire cloud coming our way, so we just ran.”

People still affected by the evacuation can visit Thompson Hall at the Umatilla County Fairgrounds, 515 W. Orchard Ave. in Hermiston, or contact 1-800-680-1455 for more information.

Contact George Plaven at gplaven@eastoregonian.com or 541-564-4547. Phil Wright contributed to this story.