Minneapolis firefighters battle large fire in Corcoran neighborhood

Crews stand outside the duplex on 21st Avenue South after Friday's fire.
MINNEAPOLIS (FOX 9) - Firefighters were forced to call in extra crews after a large fire broke out a home in south Minneapolis' Corcoran neighborhood on Friday.
Crews were called around 3 p.m. to the 3500 block of 21st Avenue South for the fire in a 2.5 story duplex.
At the duplex, crews found heavy fire from an old section of the home with flames later shooting from the roof. Crews were able to get inside the home to make sure no one was inside. But, while inside, the building suffered a partial roof collapse, forcing crews to evacuate.
From there, crews battled from the outside of the duplex until they were able to move back inside to knock down hotspots. As of 4:45 p.m., crews said the bulk of the fire had been knocked down.
Minneapolis Fire Deputy Chief Kathleen Mullen said the department was working to contact the duplex's owner.
According to reports, the home was vacant and under construction at the time of the fire.
Investigators are working to determine how the fire started.