Two men in their 20s were found dead inside a crude oil tanker at a trucking yard in south Bexar County.

According to Bexar County Spokesperson Laura Jesse, two emergency crews were called to the Pinnacle Truck, Trailer & Rail at 17601 I-35 South around 10 a.m. Tuesday.

"The victims were preparing the tanker for the venting process," Jesse said, "when other employee went to check on the men they found both males inside the tanker unconscious."

According to Jesse, one of the men was pulled from the tanker by emergency crews and given CPR.

A confined space rescue was attempted by the Lytle Volunteer Fire Department and the Somerset Volunteer Fire Department for the second man.

Jesse explained that the Pinnacle Truck, Trailer & Rail company receives tankers to vent them for 24 hours to clean the inside for crude oil.