At approximately 12:48am Box Alarm 3-03 was sounded for a reported building on fire. As it turns out, Frederick City Police Officers were already on the scene confirming fire on the interior of the Clock Shop located at 119 North East Street, in Frederick. Engine 22 was the first arriving engine company and quickly assessed the situation and requested the Safety Task Force as well as the second alarm assignment, to stage at the Frederick Fair Grounds. Chief 3-1 concurring with this request enroute. Engine 22's officer established North East Street command with the Lieutenant from Engine 31 assuming the interior sector. Interior crews reported having active fire in the 119 building, checking for extension vertically, and horizontally. Chief 3 arrived on the scene and assumed the command. Chief 3-1 taking Division A (operations). Due to another incident across town, Quint 11 was the first arriving ladder truck, assigned to side "A". Interior crews advising bulk of the fire knocked down and need for ventilation. Chief 3-1 suggesting to command to hold with the first alarm assignment only, no apparent extension beyond the building of origin. Frederick County Fire Marshall's Office requested for investigative purposes. All exposure buildings checked confirming no extension beyond fire building. Crews rehabilitated outside and swapped around for overhaul and salvage operations. Frederick County Fire Marshall's Office requesting the Maryland State Fire Marshall's Office as well as an arson detection dog from Howard County. Crews worked into the early morning assisting the Fire Marshall's Office. The cause of the fire is still under investigation by the aforementioned agencies. Fire/Rescue units clearing the scene just prior to sunrise.