(CBS) – A motorist using the McDonald’s drive-thru got more than he ordered Monday afternoon when he came across a 3-year-old boy wandering, alone, in the parking lot.

The child was discovered, wearing only underwear, outside the McDonald’s on Lawrence Avenue near Pulaski in Chicago’s Albany Park neighborhood.

The boy was first seen walking down an alley, when the male customer in the McDonald’s drive-through saw the child walking.

“He passes the kid from the window where we charge the orders and we put the kid by the crew room, to see if he has parents there, but there was no one there,” a restaurant employee tells CBS 2’s Suzanne Le Mignot.

“I asked, ‘Where is your dad, where is your mommy?’ He said, ‘My mommy is sleeping.’ So he probably just walked by the alley. He probably lives around here. So, it was crazy.”

Workers fed the hungry boy a hamburger.

The child was later reunited with his mother. As a precaution, the boy was taken to Swedish Covenant Medical Center to be checked out.

Chicago police say the child was able to sneak away by unlocking a door while his mother slept and walked away.