At least six workers cleaning a chemical tank in southeast Pakistan Friday lost their lives due to toxic fumes.

Recovery operations Saturday may discover even more fatalities, local media report.

The workers entered the 50-foot-deep tank at a Karachi factory as part of a maintenance operation. The bodies were discovered floating in water at the bottom of the tank.

It was not reported if breathing apparatus or air quality testing equipment was available. Often rescuers rushing to rescue downed workers do not take adequate precautions and become victims themselves.

As news of the disaster spread through the community, concerned family members congregated outside the factory waiting for news. Once the identities of the workers were determined family was notified.