A Coach bus flipped over into oncoming traffic when it crashed on the Long Island Expressway in Queens, killing the driver and a passenger and leaving 20 people hurt, three critically, police said Tuesday.

The bus was heading west on the expressway when it collided with another vehicle near Exit 16 at Greenpoint Ave. in Maspeth about 11:45 p.m. Monday, cops said.

That vehicle collided with a third vehicle as the force of the crash caused the bus to flip over the median into the east-bound lanes, where it collided with two other vehicles.

The 35-year-old driver of the Coach bus and a passenger were killed in the crash, cops said. Their names were not immediately released.

Medics rushed all the passengers in the bus, as well as the drivers of the four other vehicles involved — 20 patients in all — to area hospitals.

One of the drivers on the east-bound side of the highway and two bus passengers are listed in critical condition, officials said. All the other patients are expected to recover.

There were more than a dozen people on the bus at the time of the crash, officials said.

Traffic along both the east and west-bound lanes of the Long Island Expressway was shut down for hours early Tuesday as police investigated the crash.