HOUSTON (Reuters) - Two workers were hurt in an explosion early Wednesday at a hydraulic fracturing tank site in south Texas, a sheriff's dispatcher said.

A secretary for the Vann Energy Services LLC that owns the site said the men were cleaning a tank at the maintenance facility that holds hydraulic fracturing or fracking tanks in Nixon, Texas, when the blast happened. She declined to identify herself and said no further information, such as what the tanks contained, was available.

The dispatcher said the two men were flown to a hospital in San Antonio. He declined to provide further information except to say that the blast was under investigation.

(Reporting By Kristen Hays and Erwin Seba)