A 57-year-old Gunbarrel woman died when fire swept through her condo late Friday night.

The fire at the condo complex in the 7400 block of Singing Hills Drive was first reported around 11:15 p.m. Before deputies and firefighters arrived, neighbors in an adjoining condominium unit helped to evacuate a mother and daughter who were inside the unit.

Investigators with the Boulder County Sheriff's Office say the older woman collapsed shortly after escaping the fire and later died. Her 19-year-old daughter survived.

Investigators say the fire started in their unit, but could not determine the cause. They say when the sliding glass door was opened during the fire there was a flashover.

The flashover scoured all the initial fire patterns off the interior of the condo, rendering it impossible to definitively conclude where in the condo the fire started, and how it may have ignited.

The unit where the fire started and the one directly above it are a total loss. Several other units suffered varying degrees of damage from smoke and water.