Updated

An infant was among the seven people killed when a semitrailer slammed into the back of their packed minivan on an Indiana highway, and all 10 of those on board are believed to have been related, state police said Friday.

None of the minivan's occupants were wearing seatbelts when tractor-trailer rammed into their vehicle Thursday night on the Indiana Toll Road about 10 miles east of South Bend, state police Sgt. Trent Smith said.

Witnesses reported that the van appeared to have hit a deer and either slowed or stopped before the semi plowed into it at what investigators believe was about 65 mph, Smith said.

The infant who was killed had been in a car seat but had not been buckled in, he said.

The minivan had Illinois license plates, and police believe at least some of those on board were Ecuadoran immigrants living in the Chicago area, Smith said. Family members were coming from the Chicago area Friday to help identify the victims, he said.

Two of the minivan's three injured occupants were in critical condition Friday and the third was in stable condition, he said.

Witnesses suggested that the minivan may have hit a deer, then slowed or stopped before it was hit from behind by the semi, police said.

Preliminary tests indicated that the trucker had not been drinking alcohol, Smith said. He was in good condition Friday at a hospital, he said.

Investigators were able to speak with the least-injured victim, who said everyone inside the van was related.

"Not all direct family members, but cousins and other relatives," Smith said.

Both vehicles ended up in the center median, blocking traffic in both directions for several hours.