Four people are confirmed dead, 38 homes have been destroyed and seven have been damaged across 15 acres in San Bruno, Calif. from a fire that resulted from a natural gas explosion, officials said.

"I want to assure the people of San Bruno and California that we are working quickly to find the cause," Lt. Gov. Abel Maldonado said before the media.

The source of the blaze is still unknown. San Bruno and Millbrae Fire Chief Dennis Haag said that 25 percent of homes are still too hot to enter.

Chief of Health Services for San Mateo County Jean Fraser said 52 people were treated at hospitals, 15 of which arrived by ambulance.

While there are no reports of widespread looting, police said one looter was arrested Thursday night.

Maldonado said that while 75 percent of the fire has been contained, he expects the number of casualties and the extent of the damage to rise.

"The sun is shining over there but there is a dark cloud over this city," he said.

The fire started after a Pacific Gas and Electric natural gas line ruptured at 6:24 p.m. Sept. 9, triggering an explosion that set the neighborhood ablaze and still rages on.

San Bruno and Millbrae Fire Chief Dennis Haag said that a ruptured water main will likely cause problems as firefighters struggle to combat the flames.

Fire officials do not know how many people are missing.

The 1600 and 1700 blocks of Claremont Drive, the 900 block of Earl Avenue, the 1100 block of Fairmont Drive and the 2700 block of Concord Way were the most damaged from the explosion and subsequent fire, officials said.

PG&E President Chris Johns said 700 homes are currently without power and 300 are without gas. Officials said crews have been working throughout the night to restore power to those affected.

PG&E said it is working closely with the American Red Cross.

"Our hearts and prayers go out to all the friends, neighbors and families." Johns said. "We are committed to do what's right and what's appropriate to help those families."

Crews have not been able to get close enough to the source of the blaze, however, because it is highly unstable, Johns said.

The gas line was a 30-inch pipe, according to Johns, and was "probably" 40-50 years old.

San Bruno City Manager Connie Jackson said officials are in the process of setting up a local relief center and is asking people in the community to check in to ensure that they are safe.