Rescue crews were using dogs to search foot by foot through the wreckage of Joplin, Mo., hoping to find people who might have survived the deadliest tornado in decades.

Missouri Gov. Jay Nixon told NPR that the searches were being conducted “house by house, car by car, block by block” after Sunday’s twister cut a swath of destruction through the town of 50,000 at the edge of the Ozark Mountains.

“We’re still in that early stage where you’re just convinced in your gut that there are live people under piles of rubble that you’ve got to go find,” Nixon said. “Instead of counting body bags, if we can get to saving people, that’s still our goal.”

Seventeen people have been pulled from the piles of splintered wood and twisted metal left by the Joplin twister — at least the ninth deadliest tornado in U.S. history. Nixon has vowed that crews will keep looking until everyone is accounted for, but he acknowledged that the death toll of 116 is likely to climb.

The governor said a police officer from Riverside, Mo., was hospitalized and remained in serious condition after being burned by a lightning strike during the rescue effort. Another officer was slightly injured in a near-strike but kept working.

Many of the survivors in Joplin were still taking stock of the utter destruction.

“My mom lost everything,” a muddy and confused Shannon Johnson told NPR as she sifted through the rubble of a house. “She doesn’t have any clothes. We’re trying to get some clothes so my mom can change.”

Johnson said her grandmother died in the house and that her aunt is one of more than 1,100 people who were injured and getting treatment.

Scores of people were trying to salvage what they could from destroyed homes as rain and hail added to the misery in Joplin.

Willa Humphrey said she survived by hiding inside her house even though it was flattened by the twister.

“The ceilings are about to fall in… because of the rain,” she said. “If it would quit raining we’d maybe have a little more time, but we’ve to get everything out as fast as we can.”

The Storm Prediction Center in Norman, Okla., said another large tornado outbreak was a possibility in the Midwest on Tuesday.

Officials were concerned about the effect that rain and cool temperatures could have on anyone still trapped in rubble. A whipping wind, perhaps strong enough to finish off homes left barely standing by the tornado, made things more dangerous for searchers and potential survivors.

Missy Shelton of member station KSMU said 13,500 people were without power in the city.

“They are trying very hard to keep traffic out of the affected neighborhoods. One officer told me that there has been some concern about looting,” she said, reporting from Joplin.

Nixon has ordered about 140 Missouri National Guard troops to help local authorities.

“As soon as we heard the news of the tornados, the Missouri National Guard began mobilization activities,” Army Maj. Gen. Stephen L. Danner said in a statement. “Your Missouri National Guard is bringing experienced citizen-soldiers and leaders to provide the best support we have to our neighbors in Joplin.”

President Obama, currently on a tour of Europe, was expected to visit Missouri on Sunday to assess the damage.

The tornado slammed into St. John’s Regional Medical Center. The shell of the facility stands ravaged, with windows blown out. Six people died inside and more than 180 patients were transferred to the other hospital in Joplin, and facilities in nearby towns.

On the other side of town, where a strip of big box stores and chain restaurants once stood, huge front loaders were starting to stack debris. Buildings for miles around were in splinters, and cars bashed into twisted heaps of metal.

“The Home Depot is just gone … Pizza Hut, big apartment buildings,” all gone, said Joplin resident Donny Gerry.

Hundreds of businesses were leveled by the tornado as well as possibly thousands of homes, Fire Chief Mitch Randles told The Associated Press.

The twister was one of dozens reported across seven Midwestern states over the weekend. One person was killed in Minneapolis and another in Kansas, but Missouri took the hardest hits.

The disaster marks the second major tornado disaster in less than a month. In April, a pack of twisters roared across six Southern states, killing more than 300 people, two-thirds of them in Alabama.

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

He said the storm had winds of 190 to 198 mph and that it was three-quarters of a mile wide at times during its six-mile path through the city.

Once the center of a thriving mining industry, Joplin flourished though World War II because of its rich lead and zinc mines. It also gained fame as a stop along Route 66, the storied highway stretching from Chicago to Santa Monica, Calif., before freeways diminished the city’s importance.

The community, named for the founder of the area’s first Methodist congregation, is now a transportation crossroads and manufacturing hub. It’s also the hometown of poet Langston Hughes and Gunsmoke actor Dennis Weaver.

City Manager Mark Rohr said Joplin “will recover and come back stronger than we are today.”

Frank Morris of member station KCUR and Missy Shelton of member station KSMU reported from Joplin, Mo., for this story, which contains material from The Associated Press.