Power companies worked to restore electricity to thousands of customers throughout California today as a scorching heat wave threatened to push the state into a power emergency with the potential for more blackouts.

Authorities were looking into several deaths possibly related to the high temperatures, which hit the triple digits in some areas on Sunday.

With temperatures again expected to top 100 degrees, power demand was projected to reach an all-time high today and prompt some voluntary blackouts, in which some businesses agree to have their power shut off temporarily in exchange for lower rates, according to the Independent System Operator, California's power grid manager.

Those blackouts could become involuntary if customers don't conserve electricity, said ISO spokesman Gregg Fishman.

No relief was expected until at least midweek, as weather conditions conspired to bake California's normally cool coast for the fourth straight day and bring Midwest-style humidity into the usually arid Central Valley.

Heavy electricity use as people turned up their air conditioners caused blackouts throughout the state over the weekend.

Early today, some 100,000 power customers in Northern California and the Central Valley still had no electricity, along with 44,000 in Southern California. That was down from a high of 180,000 customers affected over the weekend.

More than 100 patients were evacuated from the Beverly Healthcare Center in Stockton on Sunday after temperatures reached 115 degrees and the nursing home's air conditioning gave out.

Two patients were hospitalized with heat-related stress — one died, and the other was in critical condition, said police spokesman Pete Smith.

Investigators were looking into possible criminal charges, although it was too early to tell whether the facility's operators were negligent, Smith said.

Another Central Valley nursing home, Woodland Skilled Nursing Facility, evacuated its residents when managers realized its air conditioning system wasn't operating at peak capacity, according to the state Department of Health Services. No injuries were reported there.

In Modesto, a patient at Doctors Medical Center died Saturday of heart failure apparently caused by the heat after being admitted with a 106-degree temperature, hospital officials said. Two others were hospitalized with 108-degree temperatures.

In Kern County, authorities were investigating four possible heat-related deaths, including two from the past week.

Bakersfield gardener Joaquin Ramirez, 38, may have died of heat stroke after collapsing on the job late Wednesday. And on Thursday, a woman, whose name was not released, was found dead along a bike path in Ridgecrest.

In Arizona, heat is believed to have contributed to the deaths of two transient men in Phoenix over the weekend. One, believed to be in his 50s, died Sunday, and another, a 28-year-old man, died Saturday.

The deaths came during three days of record-breaking temperatures in Phoenix. The temperature soared to 114 degrees Sunday, breaking the record of 112 degrees set in 1906. Temperatures reached 118 degrees Friday and 116 degrees Saturday, breaking the previous record for both days of 112.

Meanwhile, in St. Louis, about 237,000 homes and businesses were still without electricity today morning, down from the more than a half-million that were left in the dark last week after strong storms cut the power and temperatures soared into triple digits. Four deaths in the region were attributed to the storms or heat.

In New York, thousands of Queens residents were facing their second week without power because of a blackout that at one point affected 25,000 customers. By today morning, electricity had been restored to about 22,000 of those homes, buildings and businesses, utility Consolidated Edison said.

PHOTO CAPTION

Power lines snake their way through downtown Los Angeles in this 2001 file photo as California energy officials instituted rolling blackouts due to high temperatures and a severe electricity shortage. (Reuters)

AP