BRANT, N.Y. (AP) — A van carrying 10 people home from a Florida vacation drifted off the New York State Thruway on Thursday morning and rear-ended a state-owned dump truck moving slowly alongside the highway outside Buffalo, killing a father, his 1-month-old son and a woman passenger, state police said.

A third adult and six other children in the van were injured, along with the driver of the Thruway Authority truck that was hit around 7:45 a.m. on the eastbound side of Interstate 90 in the southern Erie County town of Brant, Capt. Douglas Montijo said.

The truck was traveling only 1 or 2 mph along the left shoulder as it followed two Thruway workers picking up trash in the median, Montijo said. There were no indications the 27-year-old driver of the van, Luis Arroyo, touched the brakes before it slammed into the back of the truck, which was mounted with a lighted arrow board, he said, adding that some of the children weren't in safety seats.

Arroyo and the infant Luis Arroyo Jr. were declared dead at the scene. Christieann Gonzalez, 29, died at a hospital.

Authorities said Jessica Gonzalez, 29, underwent surgery and was listed in serious condition Thursday afternoon at Erie County Medical Center.

Dr. Kathryn Bass, director of the Western New York Regional Pediatric Trauma Center at Women & Children's Hospital, said medical personnel were optimistic about the six children being treated there. Police said Jaicob Gonzalez, 2, and Alexis Rodriguez Jr., 10, were in stable condition. Listed in critical condition were Jaiden Gonzalez, 4, Adrianna Arroyo, 6, Yamaris Rodriquez, 8, and Alexandra Rodriquez, 13. The dump truck driver suffered minor injuries.

Police believe two families were traveling in the van while returning to Buffalo after vacationing in Florida, Montijo said.

Blankets and pillows found in the wrecked van indicate the group may have been traveling all night, possible evidence that driver fatigue may have played a role in the collision, Montijo said. The accident happened 20 miles south of Buffalo.

An 11-mile stretch of the Thruway's eastbound lanes were closed for four hours after the crash.