They say there had been news reports that people could get free food vouchers from the Federal Emergency Management Agency.
But the center was just taking names for the vouchers for people with flood damage to their homes.
Authorities report that a fight broke out about 7 a.m. with shoving and pushing, and people taking a door off its hinges.
Dozens of police and sheriff's squad cars responded to the scene.
Ambulances arrived too but there were no reports of serious injuries.