There's nothing like a record-setting heat wave, combined with a third full day without power, to get people to rediscover the joys of their local library.

Especially if that library has air conditioning and wireless Internet access when it's 100-plus degrees Fahrenheit (37.8 Celsius) under a blazing sun outside.

"It's been crazy. It's been very, very busy," said librarian Kay Bowman as noon-hour patrons both young and old flocked to the relative coolness of the spacious public library in the affluent Washington suburb of Bethesda.

On Monday, more than 400,000 homes and businesses in and around Washington still lacked power in the aftermath of fierce thunderstorms and hurricane-like winds late Friday in the national capital region.

Officials in hard-hit Maryland confirmed the state's first three heat-related deaths, and the National Weather Service said above-normal temperatures would persist "over the next few days."

Pepco, which supplies power to Washington and some of its suburbs, said its crews were toiling overtime to reconnect power lines downed by falling trees -- many of which had yet to be cleaned up.

Federal, state and local employees got the option of staying home, enabling them to avoid the frustration of erratic commuter train services or perilous intersections with no working stop lights.

With no electricity to run air conditioners, refrigerators and home computers, many residents moved in with more fortunate friends or relatives, checked into hotels -- or spent the day in the crowded library.

"Originally, I came here to study, but there's no space in there," said student Mary Mamaka, boning up for her business-school admission exams on a hard wooden bench at the Bethesda library's front door.

"Even the quiet areas are filled with people on their laptops," she said. "It's kind of hard to concentrate."

Indeed, many users made do with sitting bow-legged on the carpeted floor to get some work down or to log onto news websites for the latest developments, pressing the library's 75-port public Internet service to the limit.

Law student Emily Hagan, switching on her laptop in a place otherwise filled with shelves of books, said the power outage has left her feeling "sad" to realize how much her life now depends on uninterrupted Internet access.

Inexplicably, she said, her home has "half power" -- with no electricity for the air conditioning or kitchen stove, but some outlets still functioning. An electrician was due to come by later in the day.

On leafy Clearwood Road, decked out with US flags for Wednesday's Fourth of July holiday, but still without electricity, retiree Bill Combs looked out upon a maple tree branch outside his home that fell right onto a power line.

One live wire dropped onto his driveway, scorching its hard surface.

Bob "Digger" Townsend, part of a municipal tree-clearing team making its way down the street, said the branch would have to stay dangling on the line until Pepco crews turn up, due to the danger of electrocution.

"Any wires going through trees, we can't touch them," he said. "That's 90 percent of the problem. So many trees are down. So many wires are down. What are you going to do?"

Clearing debris from another uprooted tree, landscaping contractor Peter Albanes blamed several years of drought-like weather in the United States for weakening trees and making them more vulnerable to storms.

"This is the worst wind tree damage that I've seen in 40 or 50 years in this neighborhood," he said.