(CNN) -- At least 51 people -- including seven children at an elementary school -- were killed when a massive tornado struck an area outside Oklahoma City on Monday afternoon, officials said.
Seven children were killed at Plaza Towers Elementary School in Moore, Oklahoma, a police official said. Emergency personnel were scouring the school's rubble Monday evening, video from CNN affiliate KFOR showed. The footage also showed a number of other leveled buildings.
The tornado was estimated to be at least 2 miles wide at one point as it moved through Moore, in the southern part of the Oklahoma City metropolitan area, KFOR reported. Video from CNN affiliates showed a funnel cloud stretching from the sky to the ground, kicking up debris.
-- The city of Moore, Oklahoma, has no running water, Mayor Glenn Lewis told CNN on Monday evening. He said they're hoping to get it restored overnight.
-- President Barack Obama signed a disaster declaration for Oklahoma Monday night, a White House statement said. The declaration means federal emergency aid will supplement local recovery efforts.
-- At least 145 people have been hospitalized in the Oklahoma City area after a massive tornado hit the region Monday, hospital officials said.
-- Fifty-one people have died as a result of the storm that hit the Oklahoma City area Monday, Oklahoma's office of the chief medical examiner said.
-- The dead include seven children at Plaza Towers Elementary School in Moore, said Oklahoma City Police Department spokesman Kevin Parton.
-- Amy Elliott of the state medical examiner's office said at least 20 children were killed by the storms. It was unclear how many of those were students at Plaza Towers.
-- Storm damage has been reported in Cleveland County, which includes Moore; McClain County, which includes Newcastle; and Oklahoma County, Oklahoma Department of Emergency Management representative Terri Watkins said.
-- The preliminary rating of the Moore tornado is at least EF-4 (166 to 200 mph), the National Weather Service said on Monday afternoon.
-- President Barack Obama told Oklahoma Gov. Mary Fallin 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.
A White House statement said the Federal Emergency Management Agency has deployed a team to assist state operations, and additional personnel are ready to be dispatched as necessary. Obama told Fallin that "the people of Oklahoma" are in the first family's "thoughts and prayers," the statement said.
-- About 38,000 customers of utility OG&E were without power in metropolitan Oklahoma City after Monday afternoon's storm, utility spokesman Brian Alford said.
Alford also said the storm knocked out power to the Oklahoma City area's Draper Water Treatment Plant.
OG&E is working to restore power to the plant. City officials are asking residents to turn off their sprinkler systems and postpone washing dishes and clothes, according to a message on the city government's website.
-- Country music star and Moore native Toby Keith said in a written statement: "This storm has devastated the community that I grew up in. I rode my bike through those neighborhoods. I have family and friends in Moore. My heart and prayers go to those that have lost so much. But Moore is strong and we will persevere. God be with you all."
-- Interstate 35 in Moore, Oklahoma, was closed as a result of debris from the tornado that hit the area Monday afternoon, Oklahoma Department of Transportation spokesman Cole Hackett said. Crews were headed to the north-south highway to start the cleanup process, Hackett said.
-- "People are trapped. You are going to see the devastation for days to come," Betsy Randolph, spokeswoman for Oklahoma Highway Patrol, told CNN late Monday afternoon. She did not say how many people were trapped. "Send your prayers heavenward because there are people fighting for their lives."
-- The National Guard has been activated in response to the tornado, Oklahoma Department of Emergency Management spokeswoman Ann Lee said.
-- Will Rogers World Airport reopened around at about 6 p.m. ET, spokeswoman Karen Carney said. All flights are delayed, and at least six flights have been canceled, she said.
-- Lance West, a reporter for CNN affiliate KFOR, said people late Monday afternoon were pulling students from a classroom at an elementary school heavily damaged by the tornado that hit Moore. There are no immediate reports on the condition of the children.
-- Congressman Tom Cole, who lives in Moore, told CNN's Wolf Blitzer on Monday afternoon the damage he saw on TV looks as bad as a 1999 tornado that destroyed more than 1,000 houses in his hometown.
-- McClain County Undersheriff Bill Shobe reported Monday afternoon there is significant damage near Newcastle, Oklahoma. Shobe went on to say there are a lot of structures with damage north of Newcastle and in the town of Tuttle. Most of the damage is parallel to Highway 37, he said.
-- Moore Medical Center in Oklahoma was evacuated after it sustained damages from the tornado, a hospital spokeswoman told CNN's Sarah Baker. All patients are being evacuated to Norman Regional Hospital and Health Plex Hospital, and residents injured in the storm are being told to go to those centers as well.
-- A tornado struck just Moore, Oklahoma, south of Oklahoma City on Monday afternoon, ripping apart homes and other buildings in populated areas. The National Weather Service issued a rare tornado emergency for the Oklahoma City metropolitan area, meaning that significant and widespread damage and fatalities were likely.
Meteorologists warned residents to go underground to survive a direct hit from the tornado.