Crews were scrambled from Haslingden, Blackburn, Rawenstall, Burnley, and Hyndburn to Blackburn Road in Haslingden at around 5am.
Firefighters are continuing to fight the blaze, which spread to three shops that have flats above them.
Police have closed Blackburn Road to traffic between its junctions with John Street and Deardengate.
Crews are using one aerial ladder platform, four breathing masks, three water hoses, and a jet to douse the flames.
Lancashire Fire and Rescue Service said that that two fire engines will leave the scene as the day shift takes over in the next hour.
But they said the road closure will still be in place for some time.