OAKLAND -- An explosion and fire Friday night that caused serious damage to the foundation of an Eastlake apartment building and badly burned two men resulted from a mishap in the manufacturing of hashish oil, authorities said Monday.

The two men suspected in the drug operation, one 22 and the other 25, remained hospitalized Monday with second-degree burns. Their names were not released.

Authorities said the men had lived in a lower unit of the apartment for a few months and are suspected of heating butane to convert marijuana to hashish oil.

Something went wrong in the process, prompting an explosion of butane canisters that caused some of the building to fall off its foundation. A fire also erupted, and it took firefighters 20 minutes to control the blaze.

The men fled but showed up later at a hospital claiming they were injured in a camping accident, authorities said. They were later transferred to a San Francisco hospital for treatment.

The investigation into the explosion is continuing. The building was declared unsafe by city building inspectors and remained vacant Monday.