An elderly woman died in a house fire in San Mateo, US this morning.

The 85-year-old woman was found in a home in the 100 block of South Humboldt St.

San Mateo fire officials said they got a 911 call around 4.30am Tuesday reporting smoke and flames coming from the home.

When firefighters first got to the scene, they thought that everyone inside the house had escaped. They did, except for one person, San Mateo news media have reported.

But when seven of the eight family members finally regrouped, they realized their elderly grandmother was still inside.

“We went in and located her,” said San Mateo Consolidated Fire Dept. Marshal Robert Marshall. “We brought her out and attempted CPR but we were unsuccessful and she passed away at the scene.”

Firefighters were able to knockdown the fire by 4:45 a.m., but not before flames had heavily damaged the home.

It was not clear whether the delay in pulling the woman out would have made a difference. “That’s very difficult to say,” said Marshall. “With the advanced nature of the fire, that amount of fire would be difficult to overcome in that regard. There was a lot of smoke in the house even after the fire was extinguished, So it’s very difficult to second-guess that sort of thing.”

The Red Cross was helping the displaced family find temporary shelter.

“It’s always a sad day, You know, we always want to save people. And when we can’t, that always hits us hard,” said Marshall.

Deputy Fire Chief Kent Thrasher said a cause of the blaze was still under investigation.