Ontario Provincial Police say three people were seriously injured following an explosion at a cottage in the Kawartha Lakes region.

The incident occurred at approximately 10 p.m. on Friday at a home on Normwood Drive on Four Mile Lake between Coboconk and Burnt River.

Police initially believed they were responding to a call about a fire.

Investigators say the homeowners had noticed a strange odour and contacted a local gas company.

The two homeowners and a technician for the gas company were injured during the explosion.

Two of them had to be transported to a Toronto hospital for treatment.

The cause of the blast is still unclear.

The Ontario Fire Marshal’s Office has been called in to investigate the blast. The Ontario Ministry of Labour is also involved in the investigation.