SAN DIEGO — One person was burned Friday morning in a suspected hash oil explosion at a City Heights home.

The explosion was reported shortly after 8 a.m. at an apartment in the 3700 block of Marlborough Avenue, according to San Diego Fire-Rescue Department. Officials believe the explosion was the result of hash oil, a concentrated cannabis extract also known as honey oil, Battalion Chief Kerry-Shannon Grieser told FOX 5.

Investigators were working with the department’s Hazardous Materials team, Metro Arson Strike Team and Narcotics Task Force to confirm the cause.

Firefighters evacuated all 18 units of the apartment complex. American Red Cross was called to help the 24 residents who had been displaced.

One person was taken by ambulance to UCSD Medical Center, according to the department. The extent of their burn injuries was not known.