Dallas ? Tornadoes raked the Dallas area Tuesday, crumbling a wing of a nursing home, peeling roofs from dozens of homes and spiraling big-rig trailers into the air like footballs. More than a dozen injuries were reported.

Overturned cars left streets unnavigable and flattened trucks clogged highway shoulders. Preliminary estimates were that six to 12 twisters had touched down in North Texas, senior National Weather Service meteorologist Eric Martello said. But firm numbers would only come after survey teams checked damage today, he said.

In suburban Dallas, Lancaster police officer Paul Beck said 10 people were injured, two of them severely. Three people were injured in Arlington, including two residents of a nursing home who were taken to a hospital with minor injuries after swirling winds clipped the building, city assistant fire chief Jim Self said.

“Of course the windows were flying out, and my sister is paralyzed, so I had to get someone to help me get her in a wheelchair to get her out of the room,” said Joy Johnston, who was visiting her 79-year-old sister at the Green Oaks Nursing and Rehabilitation Center. “It was terribly loud.”

Dallas-Fort Worth International Airport canceled hundreds of flights and diverted others heading its way. Among the most stunning video was an industrial section of Dallas, where rows of empty tractor-trailers crumpled like soda cans littered a parking lot.

“The officers were watching the tornadoes form and drop,” Kennedale police Chief Tommy Williams said. “It was pretty active for a while.”

The confirmed tornadoes touched down near Royce City and Silver Springs, said National Weather Service meteorologist Matt Bishop.

April is the peak of the tornado season that runs from March until June. Bishop said Tuesday’s storms suggest that “we’re on pace to be above normal.”

Johnston said her sister was taken to the hospital because of her delicate health. Another resident at the nursing home, Louella Curtis, 92, said workers roused her out of bed and put her in the hall.

“The hallways were all jammed,” Johnston said. “Everyone was trying to help each other to make a path for others. I’d say everybody was out of their rooms within 20 minutes.”

Most of Dallas was spared the full wrath of the storm. Yet in Lancaster, television helicopters panned over exposed homes without roofs and flattened buildings. Broken sheets of plywood blanketed lawns and covered rooftops.

A pastor at one Lancaster church saw debris swirling in the wind, then herded more than 30 children, some as young as newborns, into a windowless room to ride out the storm. Nearby at the church’s school, about 60 more children hid in another windowless room near the women’s bathroom.

An entire wall of Cedar Valley Christian Academy wound up being taken out in the storm. Pastor Glenn Young said he didn’t know when the school might re-open.

“I’m a little concerned,” Young said. “This is our livelihood.”