Two hundred chainsaw-equipped workers began cleaning Houston streets of fallen limbs, and the city was in negotiation with other cities to obtain another 200 workers.

Downtown Houston was closed to the public today to enable the cleanup to begin.

Faced with a populace without air-conditioning or access to unlimited water, Mayor Bill White today turned to the federal government for help in getting a 12-megawatt generator to power the city's powerless Lynchburg Station.

The station, which pumps Trinty River water to two of the city's main purification plants, lost electricity early this morning.

The mayor has appealed to the Federal Emergency Management Agency and Hospital Corporation of America for the generator, key to restoring the city's water pressure.

Normally, water pressure is 60 pounds per square inch. After Hurricane Ike knocked Lynchburg Station out of service, pressure fell to 40 psi, prompting to the mayor to call for water conservation.

When pressure dropped to 20 psi, the mayor urged residents to boil tap water before drinking it.

White also is seeking federal help in obtaining fuel to keep the Texas Medical Center in operation and resources to assist Centerpoint Energy in restoring electrical power to about 2 million customers.

In a grimmer aspect of post-hurricane activity, rescue workers by midafternoon had launched searches for the more than 100,000 area residents who ignored evacuation orders and attempted to ride out the storm in their homes.

In Chambers County officials launched boats to hunt survivors in Oak Island and Smith Point, communities that were submerged in 15 to 17 feet over water when Ike smashed ashore earlier today.

In Galveston County, where fire personnel received 100 calls for help after they had shut down operations Thursday, city officials pleaded with the media not to photograph corpses. About 23,000 island residents are thought to have ignored the evacuation call.

Earlier today, Gov. Rick Perry announced that Galveston Island has been closed to all but emergency personnel to allow the search to take place. He said he had no information regarding possible island fatalities.

In Harris County, where 250,000 people were advised to evacuate their homes in neighborhoods vulnerable to storm surge, the list of living, injured and -- possibly -- dead has yet to be compiled.

Homeland Security Secretary Michael Chertoff today said more than 50 helicopters and other aircraft were flying as part of the massive search and rescue operation in Texas and Louisiana.

"We hope it's a small number," Chertoff said regarding possible hurricane deaths. "But we're going to have to wait and see."

He said 2.2 million Texans and approximately 130,000 Louisiana residents evacuated their homes on Ike's approach.

The resistance to the evacuation calls surprised officials.

But, said Perry spokesman, Mark Miner, "This is a democracy. Local officials put out a very strong warning. . .But you can't force people to leave their homes."

Chambers County spokesman Mike Kubik said many residents of the coastal county east of Houston ignored the calls to evacuate because of sour memories of Hurricane Rita's 2005 gridlocked evacuation.

Kubic said rescue workers will investigate an unconfirmed report that an Oak Island resident called for help, saying he was treading water on the second floor of his home but did not know how long he could continue.

In Brazoria County, where officials also worried about holdouts who refused to leave, emergency management officials this afternoon cautiously suggested the county may have escaped without fatalities or serious injuries.

Officials earlier estimated that up to 35 percent of residents in mandatory evacuation zones stayed behind.

"At least, we dodged the bullet on that," said Brazoria County Justice of the Peace Wayne DuBose. "But we took a big hit and there's a lot of damage everywhere."

At least one area death was directly attributed to the storm. Montgomery County Sheriff's Lt. Dan Norris said a woman was crushed by a tree as she slept in her home.

At midafternoon today, Houston police said they were investigating two possible carbon monoxide poisoning-related deaths connected with improperly ventilated generators.

Hurricane Ike's center hit Galveston Island at 2:10 a.m. today.

Its 110 mph winds -- Ike was a strong Category 2 hurricane -- propelled a 12.4 foot storm surge into the downtown area, leaving much of the district inundated in 6 to 7 feet of water.

Ike scoured the city's seawall, demolishing landmarks including the Balinese Room, a historic nightclub and one-time gambling establishment dating to the 1940s. Also destroyed were Murdoch's Pier and a Hooters restaurant, the latter said to have crashed into the sea at 1 a.m. with an explosive roar.

In Houston, Ike flooded streets, uprooted trees, sucked windows out of downtown high-rise office buildings, damaged Reliant Stadium -- leading to a cancellation of the Texan's Monday season-opener against Baltimore -- and left millions of residents without electricity.

Late this morning the Harris County Toll Road Authority closed the Houston Ship Channel Bridge for safety reasons, noting the bridge would reopen when winds subsided.

By 4 p.m. today, the National Weather Service said, Ike, now downgraded to a tropical storm, was moving toward Mount Pleasant with 45 mph winds.

Post-Ike analysis today presented one happy fact: The hurricane could have been a lot worse.

Ike came ashore slightly east of where it officially was expected, meaning that its northeast quadrant -- and the largest surge -- impacted Bolivar Peninsula and points up the Texas coast.

Thus, what was expected to be a 15-20 storm surge on Galveston's seawall checked in at little more than 12 feet.

Houston Mayor Bill White today admonished residents to boil drinking water and to stay off the roads this morning as emergency crews work to remove the downed power lines and debris that littered the streets in the aftermath of Hurricane Ike.

Street flooding also made many roadways impassable, White said, even for high-water vehicles.

"No matter how brave you feel, we don't need to be rescuing people who do not need to be on the roads," he said, noting that those rescue missions divert resources needed to help people facing storm-caused life-threatening emergencies.

Fire and EMS crews were back on the street by 9 a.m. after Ike's powerful winds forced them to suspend services earlier this morning, Houston Fire Department Executive Assistant Chief Rick Flanagan said. The city's 911 service has received 4,700 calls in the past 24 hours, and crews were working as quickly as possible to answer them, he said.

However, he noted the same downed power lines, billboards and trees that made driving hazardous for civilians was impeding their ability to reach some locations.

White today asked residents to conserve water because the city's water supply was reaching low-pressure levels amid a power outage at a crucial pumping station. Using tap water to bathe or clean up could lower the pressure even further, he said.

CenterPoint crews had made restoring that power a top priority, he said. Residents who absolutely must drink tap water should bring it to a rapid boil for a minute, he said, in case the supply has been contaminated. There was no evidence of contamination, but it was possible since water pressure had fallen to such a low level.

Hurricane Ike knocked electricity offline for virtually the entire Houston area as it continued to roar across the area today.

CenterPoint Energy said about 90 percent of its roughly 2 million customers were in the dark before daybreak even as the storm continued to pack a 100 mph punch with the eye still near Kingwood as of 6 a.m. That means nearly 4.5 million residents were without power and doesn't include the service area of Entergy Texas.

CenterPoint spokesman Floyd LeBlanc said downtown Houston and the Medical Center, both of which have underground power lines, were the only large areas with reliable electricity. He said CenterPoint had braced for more than half its customer base losing service, and full restoration could take "several weeks."

Entergy spokesman David Caplan said 96 percent of its customers throughout its service area -- or 380,000 -- are in the dark. Two generating stations in Bridge City and Willis are down, so they and transmission lines have to be back up before crews can focus on restoring power to customers. Caplan says the process could take weeks.

"In Galveston, Fire Chief Michael Varela, speaking to reporters in the San Luis Hotel, where the city's mayor and emergency personnel are staying, said they would respond to needs on the west end of the island first, since it was hardest hit.

At least eight to 10 feet of water was on the streets when they ceased operations, and the second half of the storm, which came after that point, was far worse than the first, he said.