A powerful explosion rocked Tacoma, a port side city in Washington, United States, on Saturday afternoon injuring many workers and shutting down highways and banning aircraft for a five-mile radius.

According to local media the incident took place as a shutting down highways and banning aircraft for a five-mile radius. Due to yet unknown causes there were to small explosion followed by one big one that pulverized the truck altogether, sending the axel flying hundreds of feet in the air before landing on a state Route 16 overpass

The driver of the truck, a man in his 60s, survived but is in critical condition at Harborview Medical Center. He works for IXL, a trucking company that contracts with Ferrellgas, a propane supplier.

The other three injured men are employees of Atlas. All are in stable condition with non-life-threatening injuries.

Firefighters remain concerned that the two tanks may yet blow. Saturday night, they continued to pour water over them, using remote control devices. Even as they do so, a fire is burning in the asphalt below the containers, fueled by leaking propane.

Deputy Tacoma Fire Chief Jolene Davis said one of the two stationary tanks contained about 11,000 gallons, and the other contained about 9,000 gallons.

A woman, who has lived in a house overlooking the foundry for 10 years, said explosions are common. "We're so used to hearing those down there," said Lindy Glamuzina. She came outside her home after the initial explosions and began videotaping the fire. When the third, larger explosion hit, "it just rocked you back," she said.