Dutchess County Sheriff's officials, who are investigating, said it appears the car, which was traveling south, crossed into the truck's lane along Route 44 at Bontecou Road at around 9 a.m.
The two children were flown to Westchester Medical Center.
Names of those involved in the accident have not been released, pending notification of next of kin.
The Dutchess County Sheriff's Office is looking for witnesses to the accident. Anyone with info should call 845-486-3820.
Check back to Daily Voice for more on this story.
Click here to follow Daily Voice East Dutchess and receive free news updates.