LOS ANGELES, JUNE 27 -- The Southwest's three ancient scourges of heat, drought and fire have hit with withering force, setting temperature records in Los Angeles and Phoenix and making the air so thin that firefighting planes and jetliners were grounded Tuesday in Arizona.

Even in the usually cool early morning hours today, the heat in suburban Los Angeles remained in the 90s. Roger Trimble, a federal official at the Boise Interagency Fire Center, said the scorching midnight heat in Arizona kept fires burning with daylight speed and intensity at the beginning of an especially threatening fire season. Six firefighters were among 11 people whose deaths were blamed on the heat and flame.

The Los Angeles City Council considered a new 10 percent mandatory cut in water use as reservoirs continued to dry up and downtown temperatures reached 109 degrees, close to Tuesday's 112 degrees, a record high here. Phoenix's 122-degree heat Tuesday also broke that city's records. It was 118 today.

Michael Jimenez, a Los Angeles City Council staff member working on the water-rationing ordinance, said the blast of heat that greeted him as he walked from his car to his Pasadena apartment Tuesday evening "made me feel like I was back on the fire line when I worked for the Forest Service."

Demand from air conditioners was so intense the city's department of water and power set a record of 5,137 megawatts Tuesday, and more demand is expected today.

In Tonto National Forest 90 miles northeast of Phoenix, five prison inmates and an administrative assistant to the warden at the San Pedro Unit of the state prison at Perryville died after being sent to battle a wildfire that spread over 15,000 acres. Brushfires broke out in several other parts of the region, damaging 28 houses in the Los Angeles suburb of Glendale and blackening 530 acres in Ventura County northwest of here.

Trimble rated the summer fire threat "very high to extremely dangerous" throughout the Southwest. He said after Phoenix temperatures passed the 115-degree mark at 2 p.m. Tuesday, both fix-winged aircraft and helicopters used to spot and drop retardant on wildfires had to be grounded because the temperatures exceeded their operational limits. Civilian jetliners also were grounded Tuesday, but airline officials sought advice from Boeing aircraft engineers on how to operate in conditions not covered in their manuals and there were no temperature-related delays today.

Steve Tracton, a meteorologist with the National Weather Service's climate analysis center, blamed the heat wave on "a very stagnant, intense high pressure system sitting over that area that has allowed the heat of the sun to do its thing." He said "there is no sign of it dissipating at all" in the next few days, although local forecasters said offshore eddies may drop temperatures here a few degrees.

California is in the fourth and driest year of its worst drought in 60 years. In response to warnings from Southern California authorities that population growth was outstripping available water sources, threatening a permanent shortage throughout the region, the Los Angeles City Council considered mandatory water cuts.

In Los Angeles, ice cream stores experienced long lines, and more than 500,000 people crowded the beaches where temperatures were often 20 degrees lower than the inland suburbs. Cars stalled by vapor lock jammed several freeways.

Fire officials here said they thought the heat contributed to the deaths of three men, one found at his home Tuesday after complaining of symptoms of heat exhaustion, one found behind a downtown building and one found on a street. Four-year-old Francisco Hernandez was found dead Tuesday inside a parked car with the windows rolled up on his street in Los Angeles's San Fernando Valley suburbs while his parents visited friends nearby. Phoenix police reported the death of a 57-year-old man who was working outdoors and whose body temperature had reached 108 degrees. The deaths of three other people Tuesday in Phoenix may have been related to the heat, but officials said they were awaiting results of autopsies.

Sustained exposure to temperatures of this magnitude can cause heat stroke, which can cut off perspiration -- the body's natural cooling system -- and lead to death. Heat exhaustion, producing dizziness and profuse perspiration, and heat cramps, particularly after exercise, are also possible. Dehydration can seriously weaken many people suffering from other illnesses, and doctors warned patients here to stay indoors and drink fluids.

"The problem is old people staying indoors {without air conditioning} and not drinking enough fluids," said Pasadena physician Fredrick McKay. "Their memory isn't so good, and after three or four days, they can become terribly dehydrated."

Four Los Angeles schools in summer session without air conditioning closed early today, and most schools kept children off playgrounds even during lunch hour. Traffic problems slackened this afternoon as many Southern Californians stayed home, pushing air conditioning demands higher.

The National Weather Service warned of damage to fruit crops. One grower said he expected his boysenberries to "cook right on the vine."

Luz International, the world's largest supplier of solar-generated electricity, was pumping close to its maximum 274 megawatts today from desert plants to Southern California customers. But that did not help Luz media manager Annalisa Erickson as she drove home Tuesday in a car without air conditioning. She said, "I kept drinking a lot of water" from a plastic water bottle she keeps in case of earthquakes.