A 12-year-old autistic boy took a flat-bed truck for a joyride on Long Island yesterday and smashed into a couple of parked cars, police sources said.

The pre-teen disappeared from Seaford and turned up about six miles away in Levittown, the sources said.

Neighbors told WCBS/Channel 2 the boy went out for a bike ride and a police alert was issued when he didn’t return.