A tractor-trailer caused a massive traffic jam after it overturned on the Brooklyn-Queens Expressway Wednesday morning.

The box truck crashed just north of the Atlantic Avenue exit in Brooklyn Heights at about 4:35 a.m in the eastbound lanes, snarling traffic for the morning rush hour.

All eastbound lanes were closed, as were some westbound lanes.

The roof broke open, spilling the truck’s contents onto the road.

Congestion even spread to local Brooklyn streets in Downtown Brooklyn and Red Hook.

Two injured people were taken to Bellevue Hospital, where they were listed in stable condition, an FDNY spokeswoman said.

It was not immediately clear what caused the accident, or why the driver lost control.