Thousands of gallons of crude oil leaked from a storage tank at Chevron's Port Arthur refinery Monday, sending at least 22 people to hospitals with respiratory problems and forcing the evacuation of up to 7,000 people, police said.

The oil began leaking about 2:15 p.m. from a 300,000-barrel storage tank at the refinery, Chevron's second-largest refinery in the United States, Chevron spokesman Johnny Green said.There was less than 100,000 barrels in the tank Sunday, said another company spokesman, Art Spencer, and officials did not know how much leaked from the facility.