CHICAGO (WLS) -- Chicago firefighters battled a large blaze Friday afternoon that spread to 5-6 businesses in an Albany Park retail block and caused minor injuries to three firefighters.The fire started at about 12:30 p.m. in the Irving Plaza Cleaners near Irving Park Road and North Elston Avenue on the northwest side. In addition to the 5-6 business, three other businesses have sustained fire damage, said Chicago Fire Assistant Deputy Commissioner Marc Nielsen. Firefighters struck out the four-alarm fire shortly before 4:30 p.m.The building has a truss roof made of heavy timbers, which was a major concern for firefighters. The roof structures are known to easily collapse in building fires. As a result, firefighters had at one point evacuated the structure and battled the blaze from the outside."Essentially we have a lumber yard above our head," Nielsen said.The firefighters who were injured stemmed from a suspected smoke explosions that caught firefighters off guard, he said. The non-life threatening injuries included smoke inhalation and minor burns. The firefighters were transported to the hospital, Nielsen said.The cause of the fire is undetermined.The retail block includes a small Chicago Public Library branch, convenience store and a formal wear store. Nielsen said they were able to stop the fire on the west end, but as of 4 p.m. the fire continued to spread east in the retail complex.Jesse Espino, owner of the dry cleaners where the fire started, said all of his nine employees escaped safely. However, he adds: "It's kind of sad to see your business falling like that."Friday evening, water used to put out the fire flooded nearby streets just north of the blaze. At some corners, such as Belle Plaine and Saint Louis, residents cleaned out catch basins.The worst flooding appears to be at Drake Avenue, where no cars can drive down the street and basements are flooding."Checked the basement, got a little bit of water," said Bill Quigley. "Not much, but not as bad as I thought it was going to be, you know."