Windsor fire officials say a house fire that caused $500,000 damage has now been determined as intentionally set.

Crews were called out to a home fire at 833 Assumption St., just before 5 a.m. Monday morning. The house next door at 835 Assumption also caught fire.

An investigator from the Office of the Fire Marshal was on scene Wednesday.

Officials say the fire started as an external fire and has been confirmed as an intentionally set fire. The incident has now been turned over to Windsor police.

Fire officials describe both structures as multi-unit residential buildings. The blaze is said to have broken through the roof of one of the buildings.