Weather Warning, Oklahoma, Kansas

OKLAHOMA CITY (AP) — Tornado sirens sounded across Oklahoma City early Saturday as the nation's midsection braced for what forecasters cautioned could be a day of "life-threatening" storms, with the most dangerous weather expected to develop in the afternoon.

At least three possible tornadoes were reported west and north of the city, though no injuries were immediately reported, said Oklahoma Department of Emergency Management official Michelann Ooten. The National Weather Service, which is working to confirm the tornadoes, said the storms damaged some homes.

The most dangerous weather, however, is expected to develop later in the day. Officials are warning that a large area spanning from Minnesota to Texas could be at risk.

"This could go into certainly to overnight situations, which is always of immense concerns to us," Ooten said.

The worst conditions were projected for late Saturday afternoon between Oklahoma City and Salina, Kan., but other areas also could see severe storms with baseball-sized hail and winds of up to 70 mph, forecasters said. The warning issued Friday covers parts of Illinois, Iowa, Kansas, Missouri, Nebraska, Oklahoma and Texas.

One of the suspected tornadoes early Saturday hit near the small town of Piedmont, taking a similar path as a tornado last May that killed several people, Mayor Valerie Thomerson said.

"Because of last year, we've had a lot of new people put storm centers into place," the mayor said, adding that no major damage had been reported. "We're all very anxious about this afternoon."

The city of Norman, home to the University of Oklahoma campus, got a preview of the potential destruction when a twister whizzed by the nation's tornado forecasting headquarters but caused little damage Friday. Norman Regional Hospital and an affiliate treated 19 people for mainly "bumps and bruises," and one patient remained hospitalized in fair condition late Friday, hospital spokeswoman Kelly Wells said.

The Storm Prediction Center, which is part of the National Weather Service, gave the sobering warning that the outbreak could be a "high-end, life-threatening event."

Director Russ Schneider said it was just the second time in U.S. history that the center issued a high-risk warning more than 24 hours in advance. The first was in April 2006, when nearly 100 tornadoes tore across the southeastern U.S., killing a dozen people and damaging more than 1,000 homes in Tennessee.

It's possible to issue earlier warnings because improvements in storm modeling and technology are letting forecasters predict storms earlier and with greater confidence, said Chris Vaccaro, a spokesman for the National Weather Service. In the past, people often have had only minutes of warning when a siren went off.

"We're quite sure (Saturday) will be a very busy and dangerous day in terms of large tornadoes in parts of the central and southern plains," Vaccaro said. "The ingredients are coming together."

The strongly worded message came after the National Weather Service announced last month that it would start using terms like "mass devastation," ''unsurvivable" and "catastrophic" in warnings in an effort to get more people to take heed. It said it would test the new warnings in Kansas and Missouri before deciding whether to expand them to other parts of the country.

Friday's warning, despite the dire language, was not part of that effort but just the most accurate way to describe what was expected, a weather service spokeswoman said.

In Norman, the Red Cross reported about 100 people at a shelter it had established at a recreation center, and most were planning to spend the night. Red Cross officials were planning to conduct damage assessments Saturday once the storms had cleared.

Video from television helicopters showed several buildings damaged in the city of about 100,000 about 20 miles south of Oklahoma City. The Oklahoman newspaper reported that among the businesses damaged was a custom cake shop, which lost a roof, windows and thousands of dollars' worth of wedding and birthday cakes.

Emergency management officials in Kansas and Oklahoma warned residents to stay updated on weather developments and create a plan for where they and their families would go if a tornado developed.

"We know it's a Saturday and that people are going to be out and about, so stay weather aware," Cain said. "Have your cellphone on you, keep it charged and make sure you're checking the weather throughout the day so you don't get caught off guard."

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Associated Press broadcast reporter Ed Donahue in Washington contributed to this report.

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