Texas tornadoes wreck homes and ground flights
Several powerful tornadoes have touched down near Dallas, in the US state of Texas, flipping trucks, wrecking homes, uprooting trees and grounding planes.
Dallas-Fort Worth Airport cancelled flights and moved passengers away from glass windows for their safety.
Meteorologists estimated that six to 12 tornadoes had touched down in North Texas. Police reported several injuries but no fatalities so far.
US TV footage showed images of houses with roofs and second storeys missing.
Some of the properties were almost completely blown away.
"Obviously we're going to have a lot of assessments to make when this is done," Dallas County spokeswoman Maria Arita told the Associated Press.
The National Weather Service (NWS) at first reported at least two "large and extremely dangerous" tornadoes.
Its warning saidthat the area would remain on tornado watch until 20:00 local time (01:00 GMT) on Tuesday.
Later, senior NWS meteorologist Eric Martello said an estimated six to 12 twisters had touched down, although survey teams had yet to confirm the numbers.
One of the tornados touched down in a parking lot full of articulated lorries, and a local television station captured the vehiclesflying through the air.
Some of the cargo containers attached to the lorries were flattened.
Witnesses said the twisters formed quickly.
"All of a sudden, the rain and hail ceased," Jonathan Cook, a resident of a nearby town, told CNN. "That's when we saw the tornadoes touch down."
Damage was reported in nearby Kennedale, Arlington and Lancaster.
Lancaster police said 10 people had been injured, two seriously.
In Arlington another three people were injured including two residents of a nursing home, fire crews said.
Kennedale city spokeswoman Amethyst Cirmo said that so far moderate damage had been reported on 40 to 50 homes as well as some businesses.
American Airlines cancelled hundreds of flights at Dallas-Fort Worth International, the eighth busiest airport in the world in terms of passengers.
More than 110 aircraft were damaged from hail.
Power cuts to tens of thousands of homes were reported in the area, and police have warned residents to stay away from dangling power lines.
April is the peak of the region's tornado season. Meteorologists said the tornadoes were the result of a slow-moving storm system centred over northern New Mexico.