MARIETTA, Ga. -- Investigators said late Wednesday morning that they are still looking for the cause of two mattress store fires that happened within minutes of each other.

The first fire broke out about 11:30 p.m. Tuesday at the Mattress Firm Supercenter on Cobb Parkway. Marietta Fire Department Deputy Chief Danny Rackley said flames were shooting through the roof of the store when firefighters arrived.

Rackley said it took crews about 90 minutes to douse the fire, which caused severe damage to the store and the strip mall the store is located in.

About eight minutes after the first fire was reported, a blaze broke out at the Mattress Firm Supercenter in a shopping center about 5 miles away on South Cobb Parkway. The second store suffered only minor smoke and water damage. Cobb County Fire Department spokesman Joseph Bryant said the sprinkler system helped contain that fire and keep it from spreading throughout the store.

Bryant said authorities are trying to determine whether the fires are connected.