Utility crews battled the dark for a fifth day on Thursday in an effort to restore power to all Ohio residents and some students went back to school for the first time since the remnants of Hurricane Ike hit the Midwest region on Sunday.

Just before dawn Thursday, a 10-mile drive up Interstate 71 from downtown Columbus to the city’s northern sections revealed several neighborhoods and large apartment complexes still in darkness. American Electric Power reported on its Web site that outages continued to affect more than a quarter of its 506,000 customers in Franklin County, which includes Columbus.

In southwestern Ohio, Taylor Chapman, 15, of Carlisle, relied on a flashlight to find her clothes and flushed her toilet with water from a nearby creek on Wednesday. About 1,700 families in her town coped by using water from creeks and swimming pools as they waited for utilities to restore power. The wind storm also incapacitated the electric pumps that supply local well water to homes.

Gov. Ted Strickland wrote a letter Wednesday requesting that the federal government declare a state of emergency in Ohio and provide about $7 million in recovery assistance.

Ohio’s utilities reported about 900,000 homes and businesses still without power, down from 2.6 million customers at some point after the windstorm hit Sunday.

Nearly 350,000 still were without power Wednesday in Kentucky, Indiana and Pennsylvania.

Utilities hoped to restore power to those still coping without it on Thursday, but some could be in the dark until the weekend.

Power restoration was delayed because damage from the hurricane-force winds was unprecedented for the region and required companies to call in crews from other states to help, utilities said. In some cases, Ohio-based crews were recalled from Texas and other southern states after having been sent there to help with Ike’s aftermath.

FirstEnergy spokeswoman Ellen Raines said Wednesday that system improvements and tree-trimming near power lines in the years since the widespread blackout of 2003 weren’t factors this week.

‘‘There is really no way to prevent outages when you have 70-plus (mph) winds that begin at 5 or 6 o’clock in the evening and go through midnight,’’ Raines said, adding the storm caused widespread system damage.

‘‘It brought down entire trees, poles and wires and it’s requiring us to rebuild entire sections of our system. There really isn’t anything you could do as a utility to prevent that,’’ she said.

Some Cincinnati-area schools were set to reopen on Thursday, while others still lacked power. Columbus city schools announced they would not reopen. Some other schools across the state were waiting on power, and others were trying to replace cafeteria food that had spoiled.

Some schools already have used three of their five allotted ‘‘calamity days,’’ which are usually used during winter weather and give students time off with no make-ups.

Officials aren’t planning to increase that allotment, said Karla Warren, a spokeswoman for the state Department of Education.

Hospitals in the Dayton area were treating patients who had fallen from roofs, strained muscles and suffered chain saw injuries while cleaning up, he said. Health officials also were inspecting reopened restaurants and grocery stores.

The hurricane is blamed for at least 50 deaths in 11 states from the Gulf Coast to Michigan. At least six deaths were reported in Ohio.

Signs of the windstorm still were evident Wednesday to commuters in the Cincinnati area. In the city’s Mount Lookout neighborhood, piles of tree limbs lined the curbs and morning commuters came to sudden stops at traffic lights that haven’t worked in days.

Suburban Cincinnati resident Bill Cunningham said he expected his power back Saturday. Until then, he’s eating takeout and looking forward to a cheaper electric bill this month.

‘‘Worse things could happen,’’ he said. ‘‘We could be in Houston.’’