Crews in Norwalk are investigating after a fire in an apartment on Thursday night. The incident occurred at approximately 5:39 p.m. on Wall Street. Firefighters said they forced their way into the unoccupied apartment to finish putting out the fire. Crews said the sprinkler system kept the fire in check. The kitchen fire scorched the countertop and cabinets and left heavy smoke in the apartment and a light smoke condition throughout the apartment building, according to crews. The sprinkler system was shut down as soon as possible to limit water damage, crews said. The apartment directly below the third-floor unit sustained minor water damage along with the basement. Firefighters said they used squeegees to push water out of the fire escape door on the two upper floors.