Three people died in San Mateo County as a result of last weekend’s record-breaking heat wave, bringing the death total in the Bay Area to six, officials said Thursday.

Patrick Henry, 90, of Pacifica; Ernesto Demesa, 79, of Daly City; and Loraine Christiansen, 95, of Millbrae; died as temperatures soared over the 100-degree mark, officials said. All three died because of shock due to heat stroke, said San Mateo County Coroner Robert Foucrault.

Christiansen lived at St. Francis Pavilion, an assisted living facility, where medical professionals determined Saturday that she was suffering from heat-related symptoms, Foucrault said. She was taken to Kaiser Permanente in South San Francisco, where she died.

Demesa lived alone. Henry lived with his wife, who called 911 on Saturday to report he was having problems, Foucrault said. He died at his home.

Neither man’s home had air conditioning, Foucrault said.

The San Francisco medical examiner said Wednesday that three people died in the city as a result of the heat. Officials said all were elderly, but they have not released their names pending notification of relatives.

All three San Francisco victims lived alone and died at home, the medical examiner said. Emergency call records showed that none of them had called for medical help before their bodies were discovered.

Temperatures peaked at 106 degrees in San Francisco on Friday, the highest ever recorded in the city. San Francisco officials set up air-conditioned shelters, including four cooling centers, opened six swimming pools for free and directed people to its four air-conditioned libraries to help the public ride out the blazing temperatures.

Supervisor Aaron Peskin called the three deaths in San Francisco “preventable.” He said better and earlier public education and outreach from the city could have saved the victims.

Officials in Bay Area’s other seven counties said no deaths were attributed to heat.

Lizzie Johnson is a San Francisco Chronicle staff writer. Email: ljohnson@sfchronicle.com Twitter: @LizzieJohnsonnn