NEW HYDE PARK, N.Y. (AP) — New York's governor says a work train and a commuter train "side-swiped" one another, causing a derailment that injured 33 people.

Gov. Andrew Cuomo says Sunday it appears a train doing maintenance work somehow violated the clearance space of a Long Island Rail Road train.

Both trains were traveling east when they collided just after 9 p.m. Saturday.

Metropolitan Transit Authority Chairman Thomas Prendergast says seven employees and 26 customers were injured. He says four people sustained serious injuries.

Cuomo, a Democrat, says the National Transportation Safety Board will determine what exactly caused the accident.

The 12-car Long Island Rail Road train was carrying about 600 people when it derailed.

Officials say workers will try to clear at least one of the two tracks for the Monday morning commute.