SPOKANE, Wash. -

Two Spokane city employees are being treated for critical injuries on Tuesday spurred by routine maintenance at Spokane's Waste to Energy Plant.

Just before 10 a.m., one of the incinerator's boilers exposed the workers to a blast of 212° F steam.

Both men have been flown to Harborview Medical Center in Seattle and are listed in critical condition.

The accident closed the plant to the public as well as commercial trash trucks.

Anybody who's suffered a thermal burn knows that the best treatment is getting your skin under some cold water as soon as possible. On Tuesday, coworkers heroically did just that, carrying the two injured men to a emergency showers just outside the boiler.

When a crane tosses garbage into the Waste to Energy incinerator, it catches on fire. Superheated gases from the burning trash go up a chimney lined with metal tubes filled with water called a boiler. One of those pipes in the boiler developed a small leak overnight.

That boiler was shut down and this morning, when two workers crawled inside the boiler to fix the leak, they were suddenly exposed to the steam.

“A piece of very molten hot remnants from the procedures there in the boiler, vaporized with water and caused the burns, so they were indeed steam burns as i think somebody already reported,” said Spokane Fire Department Assistant Chief Brian Schaeffer.

Arriving firefighters found employees waiting to guide them through the incinerator's maze of hallways to the critically injured patients.

“As well as immediately delivering medical care to the two victims so, our thanks from the fire department, to all the employees who were on site,” said Schaeffer. “They were extremely helpful.”

The injured workers have 23 years experience between them.

The boiler they were inside has been taken offline for an occupational safety investigation.

Spokane Mayor David Condon says right now, he's more interested in helping his hurt employees and their families.

“Our thoughts, our prayers, and definitely, the city's assistance. All that we have is focused on their spouses who will be going with them to Harborview,” said Mayor Condon.

Just 70 people work at the Waste to Energy Plant and so they are a close knit bunch who are obviously very upset about what happened here on Tuesday. That's why all non-essential personnel were sent home for the rest of the day to be with their families.

We still don't know if the incinerator be closed to the public on Wednesday.