Police have discounted the possibility that a bomb touched off Tuesday's spectacular fire at the Mobil oil refinery in Torrance, leaving company engineers to search for the cause of the blaze.
A Mobil spokesman said Saturday that the 730-acre refinery will remain out of operation until at least the end of this week as a result of the fire, which began with an explosion that injured two employees and two passers-by.
A telephone operator received a call 17 minutes after the 5:53 p.m. explosion from a man who said he had planted a bomb at the refinery, but police said they believe the call was a prank.
"There is no indication that it was a set fire," said Torrance Police Lt. Tom Dempsey. "We are operating under the premise that it was a crank call."
Investigators, however, are still searching for a man Torrance Fire Marshal Denny Haas described as "nervous-looking," who was seen Tuesday evening near the Torrance telephone booth that the phone company said was the source of the call.
Exploded in All Directions
The explosion occurred at a 30-foot-tall alkylation unit, which removes water and other impurities while producing gasoline, propane and butane. Haas said the unit exploded equally in all directions, indicating the possibility of a ruptured tank or pipe rather than a bomb.
The alkylation unit had been back in operation for two weeks at the time of the explosion after a one-month shutdown for routine maintenance, according to Mobil officials.
Local fire officials have turned over the investigation to a team of seven Mobil engineers, according to Tom Gregory, the Torrance plant's manager of safety and training.
Gregory said the investigation might take several weeks, or even months.
Work crews began cleaning and repairing the damaged area Friday. They will need at least five days to cut some pipes and reroute others to isolate the damaged portion of the refinery from the rest of the plant, Gregory said.
When those repairs have been completed, Gregory said, the plant will produce about 65% of its normal capacity of 75,000 barrels of gasoline a day. Full production will not be restored for weeks or months.