A four-alarm chemical fire closed two busy highways near San Jose and produced clouds of noxious smoke that injured at least three people before firefighters brought it under control, authorities said.

A passing motorist was overcome by smoke and taken to a hospital for treatment, said San Jose Police Sgt. Jim Morin. A firefighter and a police officer also inhaled fumes and required treatment, he said.The blaze was triggered by a small explosion at Altus Corp., a battery manufacturer, about 1 p.m., and about 200 employees were evacuated, said Jack Meral, a company vice president.

He said clouds of smoke, which also forced the evacuation of some nearby small businesses, were produced by the burning of a chemical called thionylchloride and hydrochloric acid.

"Essentially, breathing the smoke might cause some respiratory distress, burning in nasal passages, a cough, irritation of the eyes," said Johnna Anderson of the San Jose Poison Control Center. "It could cause problems for asthmatics or those with lung or heart problems."

She said that those who might have suffered a severe exposure to the fumes could find themselves coming down with pneumonia or other viral or bacterial infections a few days or weeks later.

"When that delicate lining of the nose or mouth is burned, the body has no more protection (against infection)," she said.

The blaze was controlled around 2:15 p.m., officials said.

The Highway Patrol said Interstate 880 and Highway 101 near San Jose were closed temporarily. A massive traffic jam ensued, with motorists backed up for about 15 miles.

At San Jose International Airport a few miles away, landings and takeoffs were only slightly affected, said spokeswoman Marily Mora.

Several thousand people visiting Great America Amusement Park, about six miles away, were not evacuated.