Dozens of people have been displaced from their homes in London, as firefighters continue to battle a growing blaze following a major house explosion Wednesday night.

Police say a vehicle slammed into a home just before 11 p.m. Wednesday, setting off the blast, and a woman has since been charged with impaired driving.

Investigators say they believe the vehicle hit a gas line.

Police confirmed Thursday morning that no one was in the home at the time of the crash, adding the building was completely destroyed in the explosion.

They say seven people -- including four firefighters and two police officers -- were taken to hospital. One firefighter is in serious condition and the other people received minor injuries.

Police say Daniella Alexandra Leis, 23, of Kitchener, Ont., was arrested and charged shortly after the incident.

Investigators say the fire is still active and has spread to several houses.

A spokeswoman for the city says about seven homes were "severely impacted" by the fire and about 100 residences have been evacuated.

London officials say in a statement that those displaced by the incident have been put up in hotels.

Investigators expect to be on scene for several days.

Keara-Lynn Douglas says she was watching TV around 11 p.m. when she felt her house shake.

She says she drove a few blocks to where the explosion occurred and saw bright orange flames engulfing a few homes.

Douglas says one home was completely destroyed with debris everywhere and that the scene brought her and a group of bystanders to tears.