DALLAS - Thousands of residents were without power and hundreds of flights canceled on Wednesday as authorities surveyed the damage a day after up to a dozen tornadoes struck the densely populated Dallas-Fort Worth area of Texas.

A trailer flies through the air as a tornado sweeps through the Dallas-Fort Worth area April 3, 2012 in this still image taken from video. [Photo/Agencies]

Hundreds of homes and businesses sustained significant damage in the outbreak that brought hail, high winds, and rain as it skipped through the area, tossing tractor-trailer trucks into the air and injuring at least 17 people.

Many of the 6.3 million area residents were forced to scramble for safety as the storm bore down during the early afternoon, when schools and workplaces were open in the fourth most populous US metropolitan area.

The early warning for the storm - the Dallas-Fort Worth International Airport was tracking the storm for more than an hour before it reached there - enabled people to get to safety, officials said.

About 22,000 homes and businesses remained without power on Wednesday morning from Texas to Louisiana, Mississippi and Oklahoma.

Some 420 American Airlines and American Eagle flights in and out of Dallas-Fort Worth International Airport had been canceled Wednesday, said Tim Smith, a company spokesman. There were 66 American planes and 26 American Eagle planes out of service, Smith said.  

About 1,400 people slept in airport terminals Tuesday night after the storms and an as yet undetermined number of passengers stranded by canceled flights were directed to area hotels, airport spokesman David Magana said.

A return to normal for the airport "will be measured in days, not hours," Magana said.

About 400 flights were canceled Tuesday at the airport, the eighth busiest in the world, and 40 incoming flights diverted. At the height of the storm, passengers were herded away from windows and into stairwells and restrooms, Magana said.

The tornadoes left "three major pockets of damage" in the Lancaster area south of Dallas, the Kennedale-Arlington area and in Forney, said Jud Ladd, chief of operational services at the weather service regional headquarters in Fort Worth.