When Lake County, Florida, sheriff’s deputy David Causey stopped to fill his department SUV with gas at a Eustis RaceTrac, he noticed a man standing nearby acting suspiciously.

Only days after an attack in Dallas that left six police officers dead and 10 wounded, Causey was concerned.

“I noticed this gentleman show up out of nowhere, standing behind my patrol car scanning the area (apparently better than I had been),” he posted on social media.

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The man stood there until Causey was finished filling up his SUV and then told him, “Thank you sir for what you do. I have your back,” Causey wrote.

“I just kind of just stood there in shock, that an elderly man was willing to possibly put himself in danger to help me, a complete stranger,” he wrote.

The man then walked to the other side of the parking lot, got into his vehicle and drove away without ever giving Causey his name.

The man was later identified as Casey DeLoach, a 73-year-old Army veteran.

He said he’d been standing guard for law enforcement officers since 2015, when Texas deputy Darren Goforth was shot and killed at a gas station.

Causey said the encounter was “amazing.”

Since the July 7 police officer slayings in Dallas, three more officers were killed by a gunman in Baton Rouge, Louisiana.