James Rushing, who lives across the street from the school, heard reports of the approaching twister and ran to the school where his 5-year-old foster son, Aiden, attends classes. Rushing believed he would be safer there.
"About two minutes after I got there, the school started coming apart," he said.
Another school, Briarwood Elementary, was also damaged by the tornado.
Oklahoma Gov. Mary Fallin deployed 80 National Guard members to assist with rescue operations and activated extra highway patrol officers. Fallin also spoke Monday with President Barack Obama, who declared a major disaster and ordered federal aid to supplement state and local recovery efforts.
In video of the storm, the dark funnel cloud could be seen marching slowly across the green landscape. As it churned through the community, the twister scattered shards of wood, awnings and glass all over the streets.
A map provided by the National Weather Service showed that the storm began west of Newcastle and crossed the Canadian River into Oklahoma City's rural far southwestern side about 3 p.m. When it reached Moore, the twister cut a path through the center of town before lifting back into the sky at Lake Stanley Draper.
The National Weather Service issued an initial finding that the tornado was an EF-4 on the enhanced Fujita scale, the second most powerful type of twister.
The Storm Prediction Center in Norman, Okla., forecast more stormy weather on Tuesday, predicting golf ball-sized hail, powerful winds and isolated, strong tornadoes for parts of Texas, Arkansas, Louisiana and Oklahoma. The area at risk does not include Moore, Okla.
Monday's powerful tornado loosely followed the path of a killer twister that slammed the region with 300 mph winds in May 1999. It was the fourth tornado to hit Moore since 1998.
The weather service estimated that Monday's tornado was at least a half-mile wide.