Nature unbound is an awesome, terrible, frightening thing to behold. And for the people of Oklahoma City, and especially for those who live in the suburb of Moore, they will never forget May 20, 2013 and the monster tornado that took at least 91 of their friends and neighbors - including 20 elementary school children.

Chicago Tribune:

At least 91 people, including 20 children, were feared killed when a 2 mile wide tornado tore through an Oklahoma City suburb, trapping victims beneath the rubble as one elementary school took a direct hit and another was destroyed.

President Barack Obama declared a major disaster area in Oklahoma, ordering federal aid to supplement state and local efforts in Moore after the deadliest U.S. tornado since one killed 161 people in Joplin, Missouri, two years ago.

Emergency crews were desperately searching the wreckage of Plaza Towers Elementary School that took a direct hit from the tornado on Monday afternoon, Oklahoma Lieutenant Governor Todd Lamb told CNN.

There was an outpouring of grief on the school's Facebook page, with messages from around the country including one pleading simply: "Please find those little children."

Another elementary school, homes and a hospital were among the buildings leveled, leaving residents of the town of about 50,000 people stunned at the devastation and loss of life.

The Oklahoma medical examiner said 20 of the 91 expected to have been killed were children. The office had already confirmed 51 dead and had been told by emergency services to expect 40 more bodies found in the debris, but had not yet received them.

At least 60 of the 240 people injured were children, area hospitals said.

The tornado - an  EF4 on the Enhanced Fuchida 5 point scale - touched down at 3:01 Central time, packing winds over 200 MPH. Cars were tossed around like toys and many homes simply disappeared. We don't know yet why there were so many deaths at the schools. Oklahoma, Kansas, and Texas have enhanced building codes for all public buildings due to the large number of tornadoes that touch down every year, but it is probable that the tornado was just too powerful and too destructive for any building to survive a direct hit.

As high as the death toll will likely go, it could have been much, much worse without the nearly 20 minutes of warning granted residents of Moore. No such warning was given in 1925 when the Tri-State Tornado touched down in Missouri on March 18 and left a 219 mile long path of continuous destruction. For most of that track, the tornado was a mile wide with winds up to 250 MPH. At 695, the death toll was the worst from a tornado in US history.

I lived through a near brush with an EF2 tornado a couple of years ago and I can attest to the three minutes it took for the tornado to roar through my neighborhood were the longest of my life. At the time, I thought of the observation by Helen Hunt's character Jo Harding in Twister: "You've never seen it miss this house, miss that house, and come after you!"

Few in Moore were that lucky.