NEW HYDE PARK - A Long Island Rail Road passenger train carrying hundreds of riders collided with a work train and then derailed in New Hyde Park Saturday night, injuring dozens of people and grinding service to a halt.

The collision and derailment happened about a half-mile east of the New Hyde Park station around 9 p.m. The 12-car commuter train out of Penn Station was heading eastbound with 600 people on board when authorities say it sideswiped a work train.

The first three cars of the commuter train left the tracks after the collision, while the work train caught fire.

Authorities say 33 people were injured, including seven railroad employees. Four people sustained injuries that are considered serious.

Train service reamins suspended in both directions on the Oyster Bay branch with limited bus service available. Limited service has been restored on the Ronkonkoma, Port Jefferson branches. Customers are urged to use other LIRR branches, including Montauk, Babylon and Hempstead.

Passengers aboard the train reported hearing a loud sound, then seeing sparks out the windows and feeling vibrations as the train apparently left the tracks.

Nassau County Executive Ed Mangano praised first responders for their fast and professional response at the crash scene, and noted that ladders had to be used to evacuate passengers through rough terrain due to the elevation of the tracks.

Gov. Cuomo toured the site of the crash with Mangano and MTA Chairman Thomas Prendergast Sunday morning. Cuomo says the "silver lining" is that more people were not seriously hurt and there was no loss of life.

Authorities say crews are working around the clock to restore service in time for the Monday morning commute, but it will be no easy feat. A crane must be used to move the four heavily damaged cars back onto the tracks before being moved away.

Sen. Charles Schumer's office says he was briefed by federal regulators on Sunday and says, "It looks like it will be human error... Probably someone who left the switch in the wrong position, and as a result, caused a maintenance train to sideswipe a passenger train."

The National Transportation Safety Board and the Federal Railroad Administration will investigate the crash.