GLENDALE — Two people were killed in a fire that broke out Sunday night in a commercial building on the 1100 block of Sonora Avenue in Glendale, California. The Glendale Fire Department received the report around 10:25 p.m.

Aerial observation showed burn damage to a portion of the second floor of the building. The Burbank and Pasadena fire departments responded to help extinguish the blaze.

No one else was injured. The identities of the two people who died have not been released.

Police said the fire is suspicious in nature because it occurred at night in a commercial building. Detectives remained at the scene Monday morning, and arson investigators are working alongside them to determine the cause. The investigation into the origin of the fire is ongoing.

The building housed a mix of tenants, including home health and hospice offices, a photography and videography business, a television station, and finance businesses. The Glendale Fire Department was the first to respond after the fire was reported, with the Burbank and Pasadena departments providing additional support to bring the blaze under control. Arson investigators joined detectives at the scene as part of the ongoing effort to determine how and where the fire started. Police have identified the circumstances — a nighttime fire in a commercial building — as the basis for treating the case as suspicious. The identities of the two victims had not been released as of Monday morning, and authorities have not indicated when that information will be made available.