Two restaurants in Portland’s Old Port, Flatbread Co. and Ri Ra Irish Pub and Restaurant, remained closed Monday after a hood-vent fire damaged the shared building on Commercial Street on Sunday afternoon.

It wasn’t clear Monday how soon the establishments will be able to reopen.

The fire started in the hood system at Flatbread Co., a harborfront restaurant that specializes in wood-fired pizzas made in clay ovens.

The cause of the fire is still under investigation.

Captain David Nichols of the Portland Fire Department said the damage was mostly contained to the hood system and areas of the roof near the hoods’ vents. Nichols said that some of the roof was removed to make sure the fire had not spread.

It took fire crews several hours to control hot spots and caused Portland Fire Chief Keith Gautreau to close one block of Commercial Street near the Casco Bay Ferry Terminal. Traffic was diverted starting at 1 p.m. and reopened around 4:30 p.m.

Thomas Cancelliere, general manager of Flatbread Co. in Portland, said the only visible evidence of fire inside the restaurant was smoke in the kitchen. He said the restoration work is underway and the restaurant will open when the building is compliant with all city and health regulations.