Four people were taken to a hospital - the driver of a propane truck and three employees of the foundry - after two propane tanks exploded around 3 p.m., said The News Tribune newspaper.
The driver of the propane truck was airlifted to Harborview Medical Center in Seattle, where spokeswoman Susan Gregg-Hanson said he was in critical condition Saturday evening. The three other injured men were listed in stable condition at St. Joseph Medical Center in Tacoma.
Tacoma Deputy Fire Marshal Kevin O'Donnal said 50 firefighters had the two-alarm fire under control by early Saturday evening. The eastbound lanes of State Route 16 remained closed into the evening as state transportation officials waited for a safe time to send bridge inspectors to check a highway overpass.
An electrical substation was damaged in the blast, knocking out electricity to about 13,000 Tacoma Power customers, said utility spokeswoman Chris Gleason. All but 200 were back within an hour. The remaining customers could be without power for a while, Gleason added.
An executive of the company said all employees had been accounted for after the explosion that was heard at least two miles away.
Atlas Foundry Director of Safety Evid Owen told The News Tribune he thinks a propane tank exploded while it was being filled.
Ferrellgas, a nationwide propane company, has two tanks at Atlas, said Ferrellgas spokesman Scott Brockelmeyer. The tanks each hold about 30,000 gallons of propane.
Joe Farmer, supervisor of the cleaning room at Atlas, was nearby when the first explosion occurred.
"It blew me off the forklift, Farmer said. "It blew out several windows. All of the buildings nearby used to have junk all over the tops of them. It's not there anymore."
Farmer estimated that between 30 and 40 people were in the foundry on Saturday.
"I'm not usually one to get too frightened. But I was pretty frightened," he said.
A woman who lives two blocks from the foundry said she heard and saw the explosions. Carvedia Martin said she thought the first blast was an earthquake, so she ran outside and saw the plume with flames shooting through it. The heat was so intense she covered her face.
"The cloud was so intense, you know, it looked like the bomb at Hiroshima," Martin said. "As I stood, the flames just rolled straight up in the air - the gas and the fire. That's when I turned and ran."
Alan Bouman, a worker at T & T Tire Factory a couple of miles away, said the blast caused lights to flicker and a door to sway open.
The foundry, which traces its history back to 1899 when the company made iron castings for the Northwest logging industry, is near the intersection of I-5 and Highway 16. The company still produces castings, but now supplies a variety of industries from shipbuilding to offshore oil drilling.