Five people in a van were among the dead, said 1st Sgt. Dave Bursten of the Indiana State Police. Four of them were Amish residents of nearby LaGrange County, Bristol Fire Chief William Dempster said.
The crash started around 6:45 a.m. on a rainy stretch of the Indiana Toll Road. The westbound lanes were narrowing to one for bridge construction over the St. Joseph River about a mile and a half ahead, and traffic had come to a standstill in the right lane as traffic merged into the left, said state police Sgt. Trent Smith.
It wasn't clear why the tractor-trailer driver, Leonardo Cooksey, 31, of Mount Prospect, Ill., did not slow down, Smith said. The semi rear-ended one vehicle, starting a chain reaction involving two other tractor-trailers and four other passenger vehicles, he said. He said warning signs had been posted along the highway up to three miles from the construction site.
"There are thousands of people that travel these roads everyday. All it takes is one person not paying attention for a split second to cause these accidents," Smith said.
No charges were immediately filed against Cooksey, who was not injured. Investigators said they would send their report to the county prosecutor for review.
Messages seeking comment were left at Cooksey's home telephone number and for a manager at New England Motor Freight of Elizabeth, N.J., where the semi was registered.
State police reported those killed were Douglas and Mary Helen George of Springfield, N.H., who were in a sport utility vehicle; pickup truck driver Mark Repp of Sturgis, Mich.; and van passengers Merle Miller, 44, of Ligonier; Lester Yoder, 36, of Topeka; and Vernan Miller, 38; Samuel Yoder, 46, and his son, Anthony Yoder, 17, all of Wolcottville.
LaGrange County has one of the country's largest Amish populations, estimated at about 14,000. Although the Amish typically do not drive motor vehicles, it is common practice in the northern Indiana community for them to hire drivers to take them to work.
The pileup left westbound lanes closed about 40 miles west of the Ohio State line.
Hours after the crash, hazardous materials workers were working to clean up diesel fuel that stood in puddles or was streaming along the roadway from the damaged semitrailers.
A crew hauled away a vehicle that was so heavily damaged it was unrecognizable. One of the tractor-trailers appeared to have fire damage, and the back end of a pickup truck was torn off.
It was raining at the time of the crash, said State Police 1st Sgt. David Boehler, but investigators did not believe weather played a role.
The accident scene about one mile east of Bristol is near a crash site that killed five people last year on the east-west tollway, also called Interstates 80 and 90.