A record heat wave has led to the deaths of 18 people in the Phoenix (search) metropolitan area, nearly all them homeless, leaving officials scrambling to provide water and shelter to the city's transient population.

For the first time in years, homeless shelters opened their doors during the day to offer respite from the blistering sun, which has delivered above-average temperatures every day since June 29. Police began passing out thousands of water bottles donated by grocery stores, and city officials set up tents for shade downtown.

Despite officials' best efforts, four people were found dead on Wednesday.

"I don't know why I'm not burnt to pieces," said Chris Cruse, 48, after taking refuge in a shelter.

Fourteen of the victims were thought to be homeless; three were elderly women found in their homes, including one whose home cooling system was not on; it was unknown whether a man found by the side of a road on Sunday had a permanent residence, police said.

"Most of us just run from air-conditioned box to air-conditioned box, so it's hard to imagine how omnipresent the heat really is for the homeless here," said Phoenix police Sgt. Randy Force.

In all of last year, the state Department of Health Services documented 34 heat-related deaths among Arizona residents. The number of illegal immigrants killed by heat-related illnesses while trying to cross the desert are counted separately.

The first deaths were reported Saturday, when temperatures soared to 113 degrees. It hit 116 degrees on Sunday. By Wednesday, the forecast still called for a high of 108 degrees. Even during the coolest part of the day Wednesday, the mercury failed to fall lower than 89 degrees.

David Waing, a former truck driver who's been living on the streets of Phoenix for the past year, said he's been staying close to water by sleeping near one of the city's irrigation canals.

"In the mornings, about 9 or 10 o'clock, when it starts getting really hot, we just jump in and take a swim," he said. "The nights aren't much better. When the wind does blow, it feels like a blast furnace."

Waing and Cruse both spent Wednesday at the Phoenix Rescue Mission (search) watching movies in the shelter's chapel, which was opened Monday to anyone needing a break from the heat.

The shelter was also turning on hoses so transients could wet their clothes and had ordered 300 neckerchiefs that can be dipped in water and tied around the neck, said Bob Reed, a shelter manager.

Reed said the shelter had also dispatched a van to deliver water to transients around town.

Meanwhile, Phoenix Mayor Phil Gordon (search) said his office was writing a letter asking Congress for a change in legislation to provide utility assistance for soaring cooling bills the same way it provides for heating bills in eastern states.

"Fair is fair. There are too many individuals dying of heat here," Gordon said.

Maricopa County, including Phoenix and its suburbs, has a homeless population between 10,000 and 12,000 people, said Gloria Hurtado, the city's human service director.