An explosion reduced a large section of a Motel 6 near Seattle to rubble late Tuesday only moments after it was evacuated due to a gas leak.

Firefighters who were on scene in Bremerton, Washington, at the time were blown back nearly 20 feet, police said.

A gas company worker was critically injured by the blast and was flown by air ambulance to a hospital with second- and third-degree burns.

Image: The scene at Motel 6 in Bremerton, Washington

Image: The scene at Motel 6 in Bremerton, Washington

A gas leak was reported shortly before 8 p.m. local time (11 p.m. ET). Motel workers and patrons were able to evacuate just prior to the blast, which happened at 8:24 p.m., authorities say.

“The shaking was bad enough that the neighbors thought a tree fell on their house,” said Alice Adams, who lives three blocks away. “Both the sound and force made it almost instantly obvious that it was an explosion and not something smaller like a firework explosion or gunshot.”

Local resident Beth Olson told NBC News: “It felt like a massive pressure concussion, like a bomb went off.”

She added: “I was sitting on my floor, as was my upstairs neighbor … and as soon as we felt the concussion, I texted him and he called me, simultaneously. He’s in the military so he was immediately concerned about that, of course.

“I could definitely feel it in my eardrums initially and when we ran outside, it was dead silent — no birds or anything, and the busy street next to us was empty — until the sirens started.”

The motel’s manager, Tonya Hinds, told NBC station KING5 that she pulled an alarm in the building before the blast. “I knew pulling it was a split-second decision I thought this could cause major pandemonium, me pulling this alarm, but my gut told me to and I’m glad I did because it gave us time to get everyone away from the building,” she said.

The blaze at the site burned for several hours.

Bremerton Police Chief Steve Strachan told The Associated Press there were no reports of anyone missing, but fire officials planned to go through the rubble carefully to make sure.

“The management did a really good job of getting the alarm in right away and getting the evacuation started,” Strachan said. “We’re very thankful there weren’t more injuries.”

Bremerton is a town of about 39,000 that’s a one-hour ferry ride across the Puget Sound from Seattle.