Courtland County Sheriff's Captain Mark Helms said the tractor-trailer was driving south on Route 13 near Truxton when the load disconnected just after 6 p.m. It hit a northbound minivan, which was carrying eight people, tearing it apart.
The adults were in their early 20s, and the children, all under 10, were from two different families, Coroner Whitney Meeker said.
The single survivor was taken to Upstate University Hospital in Syracuse, CNY Central reported. The extent of that person's injuries were not made public, and the identities of the victims were not released.
Police said the two people in the tractor-trailer were uninjured.