(CNN) -- At least 24 people -- including nine children -- were killed when a massive tornado struck an area outside Oklahoma City on Monday afternoon, officials said.
At least seven of those children were killed at Plaza Towers Elementary School in Moore, Oklahoma, police said. Emergency personnel on Tuesday continued to scour the school's rubble -- a scene of twisted I-beams and crumbled cinder blocks.
The tornado was estimated to be at least two miles wide at one point as it moved through Moore, in the southern part of the Oklahoma City metropolitan area, KFOR reported. The preliminary rating of the tornado was at least EF4 (166 to 200 mph), the National Weather Service said.
-- Members of Oklahoma's congressional delegation were planning to head back home from Washington on Tuesday in the aftermath of the devastating Oklahoma tornado. They are Sens. James Inhofe and Tom Coburn, and Reps. Jim Bridenstine, Markwayne Mullin, Frank Lucas, Tom Cole, and James Lankford.
-- Oklahoma officials have revised the death toll from Monday's powerful tornado to 24, down from 51. Nine of the fatalities are children.
-- State Rep. Mark McBride, a Republican who represents a district ravaged by Monday's Oklahoma tornado, said he and his family have endured tornadoes for decades but "this is the worst thing" he's ever seen.
-- President Barack Obama said he doesn't yet know the "full extent" of the damage after a powerful tornado slammed central Oklahoma on Monday. "We don't know both the human and economic losses that may have occurred," he said Tuesday.
-- "Oklahoma needs to get everything it needs right away" to recover from the powerful tornado, President Barack Obama said Tuesday.
-- Flags are expected to be lowered at the U.S. House of Representatives Tuesday morning in honor of the victims of a massive tornado that struck central Oklahoma the day before, House Speaker John Boehner said.
-- New York's governor expressed his sympathy for Oklahomans in the aftermath of the "horrific tornado" that swept through the Oklahoma City region on Monday. "Here in New York we know firsthand the devastation and pain caused by natural disasters, and in difficult times like these we, more than ever, stand with our fellow Americans," Gov. Andrew Cuomo said in a statement Tuesday.
-- The storm system behind Monday's twister and several on Sunday is threatening a large swath of the United States on Tuesday, putting 53 million people at risk of severe weather. In the bull's-eye Tuesday are parts of north-central Texas, southeastern Oklahoma, and northern Arkansas and Louisiana, according to the National Weather Service.
-- Oklahoma first and foremost needs donations to rebuild after tornadoes slammed the state, Gov. Mary Fallin told CNN on Tuesday.
-- More than 40,000 customers remain without power Tuesday after a powerful tornado slammed the Oklahoma City region, a utility spokesman said. More than half of those customers were in the heavily damaged suburb of Moore, according to Brian Alford, a spokesman for Oklahoma Gas & Electric.
-- Glenn Lewis, the mayor of tornado-ravaged Moore, Oklahoma, told CNN on Tuesday the rescue effort is continuing and "we're very optimistic we might find one or two people."
-- Personnel have rescued 101 people from rubble in metropolitan Oklahoma City after a tornado hit the area Monday, Oklahoma Department of Emergency Management representative Terri Watkins said Tuesday morning. Watkins cited an Oklahoma Highway Patrol tally of rescues from all agencies.
-- Some of the children killed at Plaza Towers Elementary School in Moore, Oklahoma, during Monday's storm drowned in a basement area there, Oklahoma Lt. Gov. Todd Lamb told CNN Tuesday morning. "My understanding, this school ... Plaza Towers, they had a basement. Quite frankly, don't mean to be graphic, but that's why some of the children drowned, because they were in the basement area," he said. Officials have said the storm killed at least seven children at the school.
-- Obama signed a disaster declaration for Oklahoma on Monday night, a White House statement said. The declaration means federal emergency aid will supplement local recovery efforts.
-- The president told the Oklahoma governor that the federal government "stands ready to provide all available assistance" as part of the response to a series of deadly storms that have struck the Oklahoma City area, including Monday's devastating tornado.
-- World leaders, including those in France, Germany, Pakistan and Spain, passed along their condolences to President Obama and the American people. Britain's Queen Elizabeth II expressed her "deepest sympathies" to those affected and Pope Francis urged people to pray for families of those who've died, "especially those who lost young children."
CNN's AnneClaire Stapleton contributed to this report.