NORMAN, Oklahoma - Firefighters have contained a fire at the S&B Burger Joint restaurant in Norman, Monday morning.

According to the Norman Fire Department, about 4:30 a.m., crews responded to the report of smoke inside the restaurant, located on Main Street near James Garner Avenue. 

When firefighters arrived, they reported seeing heavy flames coming out of the second floor, and heavy, thick smoke coming from inside the structure.  Authorities said this didn't give firefighters the chance to get inside, so they went defensive. 

At around 6:30 a.m., the roof of the building collapsed. The cold temperatures have made walking conditions slick due to all the water being used on the fire.

Firefighters were able to contain the fire. They remain on the scene to monitor hot spots. 

Fire officials said the fire doesn't appear to be suspicious. But the cause remains under investigation. 

News 9 spoke with the owner of S&B, Shannon Roper, who said this location opened two years ago. He has seven restaurants and recently expanded to Illinois.

Roper said he got a call about the fire at around 5:30 a.m., about an hour after it started.

News 9 has several crews on the scene. Stay with us for updates.