A single twister in Joplin on Sunday killed at least 117 people. That's the highest toll from one tornado since accurate record-keeping began, surpassing the 116 people who were killed in a single twister in Flint, Mich., on April 27, 1953.
And the Joplin figure is expected to rise. Preliminary estimates say the twister was an EF4 on the Fujita scale - the second-highest rating assigned to tornadoes based on the damage they cause.
Though the storm has passed, danger was by no means over. Fires from gas leaks burned across Joplin on Tuesday. The smell of ammonia and propane filled the air in some damaged areas. Unstable buildings also posed threats, as whipping winds threaten to finish them off.
And the forecast looks grim: a mix of warm and cold air meeting has raised the possibility of more storms in the area Tuesday night, the Storm Prediction Center in Norman, Okla., says.
The centre expects a possible large tornado outbreak in the Midwest on Tuesday and bad weather potentially reaching the East Coast by Friday.
"This is a very serious situation brewing," centre director Russell Schneider said. The Storm Prediction Center also issued a high-risk warning before the deadly outbreak in the south in April.
Joplin Mayor Mark Rohr told a media briefing Tuesday morning that the search-and-rescue effort was continuing while the weather remained good, with search dogs and handlers coming "from all over."
Fire Chief Mitch Randles said searchers were still finding survivors and bodies, but the official number of deaths remains 116. Seven survivors were found Monday, including one inside the wreckage of a Home Depot outlet.
Asked about looting, a spokesman for the state police said there had been isolated problems, but they had been taken care of. Police are checking everyone leaving the area, he said.
He urged sightseers to stay away. "Yesterday, there was a problem with sightseers coming in," he said. "Every news station is streaming this live and on the internet. If you want to watch and see the destruction, watch it on TV."
After a record-breaking April, May is shaping up to be a busy month for tornadoes. Preliminary reports suggest more than 1,000 tornadoes touched down in April alone.
The twister that hit Joplin was one of more than 50 reported across seven Midwestern states over the weekend. One person was killed in Minneapolis and another in Kansas, but Missouri took the hardest hits.
Flash-flooding warnings remained in place around Joplin through Tuesday after more thunderstorms Monday.
Amid the despair, there were glimmers of hope: rescuers pulled 17 people from the rubble, and Missouri Gov. Jay Nixon vowed that crews would keep searching until everyone is accounted for.
"They still think there are folks that could be alive," Nixon told The Associated Press. Searchlights were brought in for work to continue overnight.
U.S. President Barack Obama plans to visit Joplin on Sunday. He pledged Tuesday that the federal government will use all resources at its disposal to help Midwesterners recover and rebuild after a "devastating and heartbreaking" series of storms.
"I want everybody in Joplin, everybody in Missouri, everybody in Minnesota, everybody across the Midwest to know that we are here for you," Obama said in London.
"The American people are by your side. We're going to stay there until every home is repaired, until every neighbourhood is rebuilt, until every business is back on its feet."
Obama spoke from London, where he is on the second stop on a four-country, six-day tour of Europe. He has already made a brief visit to Ireland, and he is to appear at the G8 summit in France at the end of the week.
He is due back in Washington on Saturday night.