A used air tank for water storage was used in a fire in the San Jose, California apartment complex.
The water tank was filled with water and left on top of a damaged apartment building.
San Jose fire investigators say a propane tank was used as a source of fuel.
The incident happened at the apartment complex, where there were several water tanks.
The fire started in a tank that had leaked and spread to the neighboring apartment building, according to investigators.
They have not identified a suspect or released any information about the incident.
Officials have not released any names.