a warning that, no doubt, helped save lives. this part of oklahoma is no stranger to deadly tornados. >> downed trees and power lines blocked roads. a roof was blown off this school. >> reporter: in may 1999 the town was hit by a twister that reached speeds over 300 mile an hour. the top of the scale, an ef-5. some of the fastest winds ever recorded on earth. 36 people were killed. and the storm still ranks as one of the costliest in american history. how long will you stay on the scene in joplin? >> until everybody is found. >> until everybody is found. >> reporter: the new round of deadly storms, two years to the day, that 158 people were killed in joplin, missouri. >> i felt suction just pulling me. >> reporter: wednesday marks the two-year anniversary of the storm that also left more than 1,000 people injured. it still ranks as the deadliest. in modern u.s. history. in america's heartland there will be more severe storms on tuesday. but in oklahoma, they're hoping