Updated: 08/23/2014 10:45 PM
Created: 08/23/2014 9:02 PM KAALtv.com
By: Hannah Tran
(ABC 6 News) -- The only activity in the bare Walmart parking lot in Mason City, Iowa, is the constant retreat of customers who were told that the store is closed.
"Dispatch received a call that there was a partial roof collapse at Walmart," said Mason City Fire Department Chief Bob Platts.
Just after 8 A.M. Saturday morning, an employee flung himself into a semi truck for safety as the roof in the southeast corner of the supermarket gave way to substantial sheets of rain.
"When we got there we were able to assess if it was safe, we were able to help the employee out, and then we basically shut down the building," said Platts
It's been a while since the city saw a downpour like that. Heavy rain flooded the dips underneath the city's bridges.
"Between 8 A.M. to 8:30 A.M., the national weather service said we had just under two inches of rain in about half an hour," said Mason City Police Lieutenant Logan Wernet.
Police some cars near Shopko and Wendy's were submerged in water during those early hours.
"We had about ten cars submerged in the water," he said.
At Walmart, the employee who sought refuge in the truck did not suffer any injuries. The Mason City Fire Department were among the last allowed inside the deserted, giant super-store.
"We're still working with Walmart administrative staff to make sure that the building is safe and we're waiting for a structural engineer," said Platts.
Police say the engineer is coming from outside of the state to assess the damage and to fully investigate the cause of the collapse. Until then, the store will be closed to customers.