DALLAS — Two men are on the run after trying and failing to make off with an ATM at an On the Run convenience store in Oak Cliff early Tuesday morning.

Police said the would-be crooks backed up a pickup truck to the Exxon station at Zang Boulevard and Illinois Avenue around 3 a.m. They smashed through the front glass and tried to hook up a heavy chain to the money machine.

Store clerk Virgil Jackson was on duty at the time. "Was I scared? No, I wasn't scared," he said. "I got about 12 years, maybe 15 years in law enforcement. "

Jackson conceded that his adrenaline was pumping during the incident.

The two suspects left some valuable evidence behind, including the truck they used in their aborted attempt. Police were seen dusting the vehicle for fingerprints.

On Monday, thieves struck another Oak Cliff Exxon station, and they did get away with the ATM.

There have been no arrests in that case.

WFAA-TV photojournalist Robert Flagg contributed to this report.