USA: Most Joplin residents ignored twister warning, experts find

After 162 people got killed because of a widespread disregard for tornado sirens, officials acknowledge better system needed to emphasise severity of a siren and suggested that a "non-routine warning mechanism" be developed to make it clear when a siren should be taken seriously, reports MSNBC.

"Honestly it was a bit of a disappointment that there were so many people who didn't move to shelter after the first warning," Stammer said. "The human side is the part that's most frustrating", said Keith Stammer, who heads the local county's emergency management agency, in the report.