The country is in grief after a wild and devastating tornado hit near Moore, Oklahoma on Monday, killing at least 51 people--including 20 children--destroying homes, businesses and schools.

The state's medical examiner office said the number of death individuals were predicted to rise. Overnight, 40 bodies were expected to be transported to the office.

"This is war-zone terrible," Jon Welsh, a helicopter pilot for KFOR who lives in Moore, said scoping out the damage from air. "This school is completely gone."

The tornado hit just before 3 P.M. local time, as many children were just getting released from school and hadn't made it home yet.

Yahoo reported that two schools-Plaza Towers Elementary and Briarwood Elementary were completely washed away. KFOR-TV noted that there were at least 75 children at Plaza Towers when the tornado hit. The station also indicated that at least seven children died in Plaza Towers and at least two dozen were trapped in the rubble.

Reports indicated that the children and their teachers stayed in the school's interior, but the school soon no longer had exterior walls once the tornado hit.

There were other reports about teachers who covered children with their own bodies to protect them from the damage. Pictures of adults rescuing children who were alive went viral on the internet.

"It seems that our worst fears have happened today," Bill Bunting, a National Weather Service meteorologist in Oklahoma, said, according to Reuters.

"Our hearts are broken," Oklahoma Gov. Mary Fallin said at a news conference on Monday.

Weather officials estimated the strength of the storm to be an F4 or F5 on the Fujita Scale, which was considered the highest rating a tornado can achieve. The National Weather Service reported that the tornado first classified an F4, with winds up to 200 mph.

"The whole city looks like a debris field," Moore Mayor Glenn Lewis said on NBC's Nightly News. "Our hospital is pretty much destroyed."