Joplin, Mo. ? Rescue crews dug through piles of splintered houses and crushed cars Monday in a search for victims of a half-mile-wide tornado that killed at least 116 people when it blasted much of this Missouri town off the map and slammed straight into its hospital.

It was the nation’s deadliest single twister in nearly 60 years and the second major tornado disaster in less than a month.

Authorities feared the toll could rise as the full scope of the destruction comes into view: house after house reduced to slabs, cars crushed like soda cans, shaken residents roaming streets in search of missing family members. And the danger was by no means over. Fires from gas leaks burned across town, and more violent weather loomed, including the threat of hail, high winds and even more tornadoes.

At daybreak, the city’s south side emerged from darkness as a barren, smoky wasteland.

“I’ve never seen such devastation — just block upon block upon block of homes just completely gone,” said former state legislator Gary Burton who showed up to help at a volunteer center at Missouri Southern State University.

Unlike the multiple storms that killed more than 300 people last month across the South, Joplin was smashed by just one exceptionally powerful tornado.

Not since a June 1953 tornado in Flint, Mich., had a single twister been so deadly. That storm also killed 116, according to the National Weather Service.

Authorities were prepared to find more bodies in the rubble throughout this gritty, blue-collar town of 50,000 people about 160 miles south of Kansas City.

Gov. Jay Nixon told The Associated Press he did not want to guess how high the death toll would eventually climb. But he said: “Clearly, it’s on its way up.”

Seventeen people were pulled alive from the rubble. An unknown number of people were hurt.

While many residents had up to 17 minutes of warning, rain and hail may have drowned out the sirens.

Larry Bruffy said he heard the first warning but looked out from his garage and saw nothing. “Five minutes later, the second warning went off,” he said. “By the time we tried to get under the house, it already went over us.”

As rescuers toiled in the debris, a strong thunderstorm lashed the crippled city. Rescue crews had to move gingerly around downed power lines and jagged chunks of debris as they hunted for victims and hoped for survivors. Fires, gas fumes and unstable buildings posed constant threats.

Teams of searchers fanned out in waves across several square miles. The groups went door to door, making quick checks of property that in many places had been stripped to their foundations or had walls collapse.

National Weather Service Director Jack Hayes said the storm was given a preliminary label as an EF4 — the second-highest rating assigned to twisters based on the damage they cause.

Hayes said the storm had winds of 190 to 198 mph. At times, it was three-quarters of a mile wide.

Some of the most startling damage was at St. John’s Regional Medical Center, where staff had only moments to hustle their patients into the hallway. Six people died there, five of them patients, plus one visitor.

The storm blew out hundreds of windows and caused damage so extensive that doctors had to abandon the hospital soon after the twister passed. A crumpled helicopter lay on its side in the parking lot near a single twisted mass of metal that used to be cars.