Police are investigating a marijuana grow operation discovered as firefighters were battling a house fire in Northridge Thursday morning.

Los Angeles Fire Department crews responded to the single-story home in the 16900 block of West Tupper Street around 4:30 a.m.

Fire was showing when the first responders arrived, Los Angeles Fire Department spokesperson Margaret Stewart stated in a news alert.

At one point, the flames extended into the attic, prompting firefighters to conduct an extensive ventilation operation on the roof.

Thirty firefighters managed to extinguish the fire in just over half an hour.

“The contents of the home indicate a marijuana grow operation,” Stewart stated.

Los Angeles Police Department investigators were called to the scene to investigate the operation.

The cause of the fire was also under investigation.