RICHMOND, Calif. (AP) — Nine people have sued Chevron Corp. over a California refinery fire that sent thousands to hospitals with respiratory issues and contributed to higher gasoline prices on the West Coast.

The lawsuit filed Wednesday in Contra Costa County Superior Court claims Chevron was grossly negligent in its handling of refinery maintenance as well as emergency response to the blaze in Richmond.

The suit was filed by attorney John Burris and two colleagues on behalf of the nine people, including three children. The attorneys expect more plaintiffs to join the case and said a class-action suit is likely against Chevron.

"They had information at the very outset that the pipes that were in that area were old, subject to leaks and failed to take any action accordingly," Burris has said. "That was last year, 2011."

San Ramon-based Chevron said it will review the lawsuit.

The area around the refinery was engulfed by a towering vapor cloud before a volatile blaze ignited on Aug. 6.

The lawsuit says some of the plaintiffs showed symptoms such as wheezing, dry heaving, seizure and difficulty breathing.

The suit also asks the court to require Chevron to establish a more effective early warning system, create protocols to shut down equipment, and appoint a monitor to oversee the new protocols and equipment.

The refinery produces 16 percent of the daily gasoline supply for the West Coast. The fire knocked out a unit that makes a specialized blend of cleaner burning gasoline that satisfies air quality laws in California, Oregon and Washington.

Since the fire, the refinery's reduced output has helped send gas prices rising in the region, with the average price of a gallon of regular climbing above $4 in California.

On Thursday, U. S. Sen. Ron Wyden, D-Ore., sent letters to the Federal Trade Commission and the Energy Information Administration asking officials to make sure oil companies "are not taking unfair advantage of the situation to jack up prices."