Fire inspectors are investigating the cause of a fire that broke out in downtown London early Wednesday morning.

Fire officials say they were called to 430 Richmond Street around 4:45 a.m. after a general alarm led to the discovery of smoke in the building by a business owner.

The building houses Macro Foods and David’s Bistro and is beside Artisan’s Alley.

According police the fire broke out between the second and third floors of the building. The businesses are on the first floor. No one was inside at the time of the fire and it is unclear if any one occupies the apartment units where the fire began.

Fire officials say much of the damage was centered around the back of the building and within the walls of the upper units.

David’s Bistro had to be ventilated due to some smoke, but damage appears to be at a minimum.

Several fire lines could be seen down Artisan’s Alley. At this time officials are still determining a total damage assessment.

Richmond Street was closed throughout the morning between Dundas Street and Queens Avenue, but was expected to open again around 9 a.m.

Investigators will be working throughout the day to try and determine the cause of the fire.