Oklahoma tornado wreckage
Overturned cars are seen after a huge tornado strikes near Oklahoma City, Monday, May 20, 2013. Reuters

One of the worst tornadoes to hit the United States in years has claimed at least 51 lives, the Oklahoma state medical examiner says. The nation, including some of its biggest celebrities, took to Twitter on Monday to mourn the victims, sending prayers and condolences with #PrayForOklahoma.

The natural disaster leveled homes and a school in the Oklahoma City area and rescue workers were still searching through the rubble for survivors Monday night. One building that was claimed by the monstrous twister was Plaza Towers Elementary School in Moore. Sean Reynolds from Weather Center Live tweeted that at least a dozen children were reportedly killed, but the total is unknown.

Among the reactions:

My heart goes out to everyone feeling the impact of the tornadoes in the OKC area. Stay safe and #PrayForOklahoma.