One of the most fundamental safety tips that police dole out is to not leave your keys in your vehicle's ignition with the doors unlocked.

But that is precisely what a D.C. police sergeant did Monday afternoon in Southeast Washington. When the officer’s back was turned while investigating a missing person complaint, police said a juvenile jumped into the driver’s seat and sped off.

“Obviously, the vehicle should be secured,” said Cmdr. Robert Contee, who heads the 6th District station. “Clearly, that wasn’t done.”

The joy ride was short-lived. The young driver headed around the block — from the 1600 block of Fort Davis Place to R Street SE, near Pennsylvania and Alabama avenues — before crashing into a barrier or fence near a house, Contee said. The driver escaped, and witnesses could not pinpoint an age. Contee said the squad car had minor damage, and there were no weapons inside.

Contee said the sergeant had parked about 12:20 p.m. to investigate someone who dialed 911 but hung up before talking to an operator. It turned out to be a missing person complaint, and the sergeant was standing outside his car talking on his cellphone when the cruiser was stolen.

The police commander said the sergeant was facing away from the cruiser and had left the door unlocked and the keys in the ignition. He did not think the car was still running.

Contee said there will be an investigation and that the sergeant faces discipline.

Peter Hermann covers crime for The Washington Post.