A blast occurred at Intel’s Arizona plant outside Phoenix on Tuesday injuring seven workers, one with severe burns.

The building was evacuated immediately after the blast.

The blast occurred after 2 p.m. local time at a large Intel campus in Chandler, Arizona, Chandler Fire Department Battalion Chief Brad Miller told Reuters.

“The accident site was under construction and that production was uninterrupted,” a spokesman for the world's leading chipmaker said.

Miller said four workers were taken to local hospitals with major injuries and three others were treated at the scene.

The incident was a flash explosion, Miller said adding that the extinguishing system quickly doused flames with a combination of water and foam. The extent of damage was not immediately clear.

The incident occurred in a solvent waste treatment room at Fab 22 close to Fab 32 which manufactures 22nm chips, a Phoenix Business Journal reported.

The multi-storey building and plant evacuated several hundred employees and it will remain closed indefinitely as authorities investigate the cause, Miller said.

Until we identify everything involved, there's no way we can say when people will be back to work, he told Reuters, adding that 10 other buildings on the campus remain opened.

Intel's website said its fabrication facilities in Arizona manufacture the company's Pentium processor family of products.