CHICAGO (CBS) — Meteorologists believe the deadly storm at the Indiana State Fair on Saturday may have been caused by a “gustnado.”

WBBM’s Mary Frances Bragiel reports, a gustnado forms when a strong wind just before a thunderstorm causes the air to circulate

Meterologists came to the possible “gustnado” conclusion after reviewing the video which they say showed a swirl of dust that flew across the stage causing it to collapse.

“In the video, it appears that a possible gustnado traveled from left to right across the stage area,” Margusity said. “The video shows a swirl of dust coming across the stage, and it’s only when the swirl hits the stage that the stage actually collapses.”

“Gustnados” are typically found in open fields, and last for seconds, Margusity said.

Five people were killed and several injured after the stage collapsed before Sugarland took the stage on Saturday night at the state fairgrounds in Indianapolis. Wind gusts of at least 50 mph–and possibly over 60 mph–were reported in the area.

LISTEN: WBBM Newsradio’s Mary Frances Bragiel reports