Tornadoes and violent storms raked through North Texas on Tuesday, crumbling the 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.

Preliminary estimates indicate as man as 12 tornadoes touched down in North Texas, senior National Weather Service meteorologist Eric Martello said. But firm numbers would only come after survey teams checked damage Wednesday, he said.

LANCASTER

In Lancaster, cars were overturned and roofs ripped from homes near Wintergreen and Roan. Initial estimates are than 300 structures including homes had been damaged and more than a dozen destroyed. Lancaster Police Officer Paul Beck said 10 people were injured, two of them severely.

NBC 5's Ken Kalthoff said some people suffered minor injuries and that people stumbled from their homes confused and scared following the storm.

Chopper 5 showed exposed homes without roofs and flattened buildings. Broken sheets of plywood blanketed lawns and covered rooftops.

Devlin Norwood said he was at his Lancaster home when he heard the storm sirens. He said he made a quick trip to a nearby store when he saw the funnel-shaped tornado lower, kick up debris and head toward his neighborhood.

"I didn't see any damage until I got back home. We had trees destroyed, fences down, boards down, boards penetrating the roof and the house, shingles damaged," said Norwood, 50, an accountant and graduate student.

The storm pushed cars into fences and toppled trees. Branches and limbs scattered across lawns and residential streets, and in one driveway, a tow-behind RV was left torn apart and crumpled.

A pastor at one Lancaster church saw debris swirling in the wind and 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. Glenn Young, the pastor, said he didn't know when the school might reopen.

"I'm a little concerned," Young said. "This is our livelihood."

One-hundred-fifty people have taken shelter at the Lancaster Recreation Center at 1700 S. Veteran's Memorial Parkway.

DALLAS

Chopper 5 spotted trailers from big-rigs tossed end-over-end, hundreds of feet into the air, near Bonnie View Road and Interstate 20 as a tornado pushed through Dallas County.

Fifty tractor-trailer trucks were damaged at Schneider National.

"Obviously we're going to have a lot of assessments to make when this is done," Dallas County spokeswoman Maria Arita said.

In the Stagecoach Trail area of the city, 47 houses were damaged. The city deemed 40 homes were deemed uninhabitable, and seven were destroyed.

An apparent twister picked up a tractor-trailer and dropped it on a couple's home off Stagecoach Trail.

"On the weather station, you see devastation like this, but I've never seen it in real life, up close and personal," said homeowner Jesse Wilbur.

A set of tires sat in what was Wilbur's living room, and his kitchen was turned upside down. Clothes were about all he and his wife could salvage before they headed off to a nearby Red Cross Shelter.

"It's a lifetime of work -- it's gone," said Wilbur.

Dallas Mayor Mike Rawlings toured the devastation Tuesday night.

"This is heartbreaking," he said. "The great news is everyone is alive, and we are thankful for that."

The city reported that seven houses had roof damage in the Tioga/Texas College neighborhoods.

Shelters were set up at Tommie Allen Recreation Center at 7071 Bonnie View Road and Kiest Park Recreation Center at 3080 South Hampton Road.

ARLINGTON

Arlington Mayor Robert Cluck declared a state of disaster because of tornado damage. An estimated 428 homes have been damaged, including a nursing home.

Three people were injured in Arlington, including two residents of a nursing home in the 3000 block of West Green Oaks Boulevard who were taken to a hospital with minor injuries after swirling winds clipped the building, 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."

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."

The Salvation Army has set up disaster shelter at a community center at 712 W. Abram Street in Arlington. Officials said gas lines have been ruptured in the city and anyone who smells gas should call 911.

Beginning at 6 a.m. Wednesday, only credentialed residents will be able to gain access to some of Arlington's more heavily-damaged neighborhoods. Residents will be issued temporary permits valid for Wednesday only. Permits can be obtained at the controlled access points to the neighborhoods and residents must show proof of residency including a state identification card or utility bill. Permanent permits will be required beginning Thursday and those can be obtained at the Arlington West Police Service Station on 2060 W. Green Oaks Boulevard.

KENNEDALE

Debris littered neighborhoods in the city of Kennedale after an apparent tornado tore through the center of town.

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

Only minor injuries were reported, but there was significant damage to residential and commercial structures.

NBC 5's Lindsay Wilcox showed at least one home where the tornado drove pieces of a fence into drywall on the interior wall of a home.

The National Weather Service will assess that damage to classify Kennedale's tornado on the Enhanced Fujita tornado damage scale.

FORNEY

The city of Forney in Kaufman County reported that 73 homes sustained damage after two tornadoes touched down. Of those, 22 homes sustained severe damage.

The area north of Highway 80 in the Diamond Creek Subdivision had the most damage. Crosby Elementary also had some roof damage. Children there were evacuated to nearby Criswell Elementary well before the tornadoes touched down, and parents picked them up from there.

The Forney Police Department is enforcing a curfew of 9 p.m. to 6 a.m. Officers will be stationed at every Diamond Creek intersection to check identification. Only residents of the neighborhood will be allowed to enter during the curfew.

Seven people were injured. Three taken to the hospital, and all were said to be minor injuries.

Margarita Ventura, who has lived in the neighborhood for about six years, said she had a tough time getting to her home after police blocked off her street.

"This is ridiculous. My whole house -- it's gone," she said choking back her tears.

A few yards away, Chris Wilson's stairs could be seen with no roof above to shield the rooms on the second floor.

"My wife could have been in the bedroom -- it's gone. My son could have been in his bedroom -- that's gone," said Wilson, adding that it could have been worse.

In front of Crosby Elementary, a car was overturned and a roof air-conditioning unit was on the ground.

The school will be closed on Wednesday, and the mayor and city leaders will assess when to open it.

A shelter has been set up at Mustang Community Church at 13851 FM 548.

The city of Forney is taking donations of food, water and clothing for those affected by the storm. Donations can be dropped off at the C-Life Church at 204 FM 1641. Phone: 972-809-9709

DFW AIRPORT

American Airlines canceled more than 450 arriving and departing flights at it hub airport by late Tuesday afternoon.

DFW Airport spokesman David Magana said more than 110 planes were damaged by hail. It wasn't clear how many belonged to American Airlines, but American and American Eagle had pulled 101 planes out of service for hail-damage inspections.

Flights also were canceled at Dallas Love Field, which is a big base for Southwest Airlines. That airline canceled more than 45 flights in and out of the airport by Tuesday evening. For a short time Tuesday afternoon, controllers in the tower at Love Field spotted a tornado headed their way. Passengers and employees were sheltered in place.

THE TORNADO OUTBREAK

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."

Baseball-sized hail was reported in nearby Euless with ping-pong-ball-sized hail reported at locations throughout North Texas.

According to Oncor Electric Delivery, approximately 9,400 customers in the Dallas-Fort Worth area were without power shortly after 2 a.m. About 20,700 customers had been without power at 8 p.m. At the storm's peak, nearly 50,000 customers had lost power.

The Dallas Chapter of the American Red Cross has already begun calling on volunteers to help those in need. If you'd like to volunteer, click here.

Gov. Rick Perry has activated the State Operations Center to quickly mobilize any assistance that North Texas authorities may need.

Associated Press writers Terry Wallace and David Koenig in Dallas, Schuyler Dixon in Arlington, Texas, Betsy Blaney in Lubbock, Angela K. Brown in Fort Worth and Paul J. Weber in San Antonio contributed to this report.