A huge tornado touched down on Monday near Oklahoma City, and the National Weather Service urged residents to immediately take cover as a massive storm system in the middle of the country threatened to pummel as many as 10 states.
"The tornado on the ground right now is huge and has hit through populated areas," Oklahoma Governor Mary Fallin said on CNN. She said it was too early to know the extent of the damage, but live television showed extensive destruction in the area.
There were no immediate reports of injuries or deaths from the tornado, which was near Moore, Oklahoma, in the Oklahoma City metropolitan area.
National Weather Service meteorologist Brynn Kerr said a tornado warning had been issued for two counties in central Oklahoma. A warning means that residents should immediately find shelter.
Two people were killed on Sunday from tornadoes in Oklahoma and at least 39 were injured.
The National Weather Service predicted a 10 percent chance of tornadoes in parts of Texas, Oklahoma, Arkansas, Kansas, Missouri and Illinois. It said parts of four other states - Wisconsin, Indiana, Michigan and Iowa - have a 5 percent risk of tornadoes.
The area at greatest risk includes Joplin, Missouri, which on Wednesday will mark two years since a massive tornado killed 161 people.
The latest tornado in Oklahoma came as the state was still recovering from a strong storm on Sunday with fist-sized hail, blinding rain and tornadoes.
Two men in their 70s died in the storm, including one at a mobile home park on the edge of the community of Bethel Acres near Oklahoma City, said Keli Cain, a spokeswoman for the Oklahoma Office of Emergency Management. Thirty-nine people were injured around the state as storms toppled trees and tore up rooftops, she said.
Several hundred homes and buildings were thought to have been damaged or destroyed and approximately 7,000 customers were left without power in Oklahoma. "There is definitely quite a bit of damage," Cain said.
Fallin declared 16 counties disaster areas, and she and other local and state officials were touring damaged areas on Monday morning.
More than two dozen tornadoes were spotted in Iowa, Oklahoma, Kansas and Illinois, according to the National Oceanic and Atmospheric Administration and local news reports. Hail stones, some as large as baseballs, were reported from Georgia to Minnesota, NOAA said.
Wind gusts of 72 miles per hour (115 kilometers per hour) were reported near Gardner, Kansas, and 60 mph in Atchison, Kansas. The high winds toppled trees, downing power lines and smashing cars and rooftops in communities around the Midwest.
A tornado that touched down southwest of Wichita, Kansas, on Sunday afternoon was rated an EF1 on Monday by the National Weather Service. The most powerful is an EF5. The tornado stayed on the ground for about 4.5 miles, with winds of 86-110 mph, the service said.
The tornado damaged homes and outbuildings, felled trees and knocked out power to about 11,000 residents but caused no injuries, said Sharon Watson, spokeswoman for the Kansas Division of Emergency Management.
"We came through this one very fortunate," Watson said.
In southwest Missouri, a tornado touched down shortly after midnight Monday in Barton County, said Tom Ryan, the county's director of emergency management. The tornado damaged some farm buildings and two houses but caused no injuries, he said, noting that it struck in a rural area.
Just east of Barton County, in Dade County, the tornado tore off roofs at a grocery store, golf course and city swimming pool complex in Lockwood, said Bob Kitsmiller, director of emergency management for the county, adding that no injuries were reported.
Forecasters were particularly aggressive in issuing warnings on Sunday evening. The National Weather Service's storm prediction center in Norman, Oklahoma, posted a Twitter alert on a tornado about to strike Pink, a town on the edge of Oklahoma City.
"Large tornado west of Pink!" the post read. "Take cover RIGHT NOW in Pink! DO NOT WAIT!"
The storm also prompted an unusually blunt warning from the central region of the National Weather Service, which covers 14 states.
"You could be killed if not underground or in a tornado shelter," it said. "Complete destruction of neighborhoods, businesses and vehicles will occur. Flying debris will be deadly to people and animals."
Pat Slattery, National Weather Service spokesman for the U.S. Central region, said the advisory was part of a new warning system reserved for severe tornadoes with the potential to form into "supercell" storms, which produce powerful winds and flash flooding.
The tornado season in the United States had been unusually quiet until last week, when a tornado struck the town of Granbury, Texas, killing six people.
(Reporting by Carey Gillam, Kevin Murphy, Steve Olafson, Jane Sutton, Chris Francescani and Ian Simpson; Editing by Doina Chiacu, Xavier Briand, Greg McCune and Leslie Adler)