They also say a man is facing charges in the incident that occurred on Route 303 in Blauvelt just after 12 p.m.
Police say 20-year-old Thomas Robb, from the United Kingdom, was driving the wrong way on a one-way section of Greenbush Road when he hit a car while driving into the intersection, which then collided with another car.
Everyone in all three cars were taken to the hospital. A 6-year-old and 7-year-old are both in critical condition.
Robb faces numerous charges, including assault in the second degree and leaving the scene with serious physical injury, both of which are felonies.