DALLAS (AP) — Travel began to slowly return to normal as temperatures warmed in North Texas on Monday following an ice storm that forced the cancellation of hundreds of flights, closed schools and cut electricity to thousands of homes and businesses.

The Texas Department of Transportation said in a late Sunday statement that it had reopened all major highways in the areas hardest hit by the wintry weather. Bridges could remain icy and the agency urged drivers to use caution Monday as the National Weather Service forecast temperatures would be in the upper 30s, giving way to warmer conditions and sunny skies by Tuesday.

Over the weekend, church services were canceled, some businesses closed and grocery stores scrambled to keep up with demand in the Dallas-Fort Worth area due to the freezing temperatures.

Fort Worth-based American Airlines and American Eagle canceled 700 flights on Monday, mainly in North Texas. The carriers on a typical day operate about 3,500 flights, said spokeswoman Dori Alvarez.

About 650 people were stranded Sunday night at Dallas-Fort Worth International Airport, said David Magana, an airport spokesman. About 2,000 travelers were stranded there on Saturday night, while Friday night about 4,000 travelers were stranded, he said. Four of the five regularly used runways were open Monday.

"It's signs of progress," Magana said.

Dallas-based Southwest Airlines operated a normal schedule Monday at Love Field, the carrier said in a statement.

Oncor, a Dallas-based electric utility, said about 22,000 homes and businesses were still without power Monday afternoon. Outages peaked at 270,000 at the height of the storm Friday.

Dallas Area Rapid Transit, which had halted train service since Friday due to ice on the tracks, offered a combination of rail and bus services Monday morning. DART said in a statement that it tested tracks, power systems and vehicles Sunday before resuming service.

Thousands of students in North Texas whose classes were canceled Friday were out of school again at the start of the week because of lingering icy conditions. The Dallas and Fort Worth school districts, along with the University of North Texas in Denton and UT-Arlington, also canceled classes.