Residents in El Segundo, some 20 miles (32km) southwest of Los Angeles, reported feeling a major blast around 21:30 local time (04:30 GMT) on Thursday, with orange flames and plumes of smoke visible around the refinery.
City officials say there is no public threat or evacuation orders currently in place. The cause of the blast is under investigation.
In a statement, Chevron called it an "isolated fire" and said that "all refinery personnel and contractors have been accounted for and there are no injuries".
No evacuation orders for area residents have been put in place by emergency response agencies monitoring the incident, and no exceedances have been detected by the facilities fence line monitoring system," the company said.
It is unclear how much damage the refinery suffered from the explosion and fire.
The Chevron refinery is located near the Los Angeles airport and supplies jet fuel for its operations though there was no immediate impact to the facility, LA Mayor Karen Bass said in a statement.
Flights at the airport are operating as normal.
The El Segundo refinery, built in 1911, is Chevron's second largest in the US and produces 285,000 barrels of crude oil every day.
It supplies a fifth of all motor vehicle fuels and 40% of the jet fuel consumed in southern California, Reuters reported.
El Segundo Mayor Chris Pimentel said firefighters were able to respond immediately to the blast.
"Our station is about a .25 mile away from the gates of Chevron," Pimentel told reporters. "Obviously, we are very concerned, and there is a lot of investigative work to be done to see what has happened."
The blaze was visible as far as Los Angeles and filled the air nearby with the smell of petrol.
In addition to investigating the explosion, officials in the city of El Segundo said they are monitoring air quality levels for signs of pollution.
One nearby resident, Mark Rogers, told the Los Angeles Times that the blast was startling for people nearby.
"I thought we got nuked or something," Mr Rogers told the local newspaper. Another resident, Keith Mohr, said the flames looked like they were "300-foot".
"I didn't know if a plane crashed or there was an earthquake or both," he said.
