NATIONAL CITY, Calif. (KABC) -- An accident at a San Diego County crematorium sent clouds of smoke containing human remains into the air on Thursday.The incident was reported at 12:15 p.m. at the Cortez Family Crematorium in National City, according to ABC News affiliate KGTV National City Fire Captain Brian Krebs told KGTV that the oven door failed to close while the furnace was in use. This sent heavy smoke out of the chimney as well as the open doors of the building.There were human remains in the smoke, Krebs confirmed. The smoke activated the building's fire extinguisher, creating a toxic smell.The plume containing the human remains moved east across National City Boulevard and Broadway toward a shopping center containing a Best Buy and a Walmart, a witness told KGTV. The smoke continued for at least half an hour.The possible health impact of inhaling the smoke is unclear. KGTV said it has reached out to San Diego County health officials about the incident.