ELLABELLE, Ga. » Five nursing students died early Wednesday in a chain-reaction crash in southeast Georgia that authorities said began when a tractor-trailer failed to slow down and smashed into stop-and-go traffic.

Those killed were traveling on Interstate 16 near Savannah in two passenger vehicles mangled by the crash. The tractor-trailer plowed into an SUV, then rolled over a small passenger car that burst into flames, said Sgt. 1st Class Chris Nease of the Georgia State Patrol. The big truck came to a halt after slamming into the back of a tanker.

All five of the dead were nursing students at Georgia Southern University in Statesboro, about 30 miles from the crash site. St. Joseph’s/ Candler Health System said the students were commuting to St. Joseph’s Hospital in Savannah for their last day of clinical training of the school year.

"The loss of any student, especially in a tragic way, is particularly painful," Brooks Keel, president of Georgia Southern, said in a statement. "Losing five students is almost incomprehensible."

The Georgia State Patrol said three people also were injured and seven vehicles were damaged.

The crash occurred at about 6 a.m. in Bryan County, about 20 miles west of Savannah. Traffic was heavy at that hour because an unrelated wreck about a mile ahead that forced motorists to slow, Nease said.

"Traffic was sort of stop-and-go when the tractor-trailer came along and struck one of the passenger vehicles in the rear," Nease said. "We’re still trying to piece it all together. It’s a terrible day."

The university said the students were all Georgia residents in their junior year — Emily E. Clark, 20, of Powder Springs, Morgan J. Bass, 20, of Leesburg, Abbie L. Deloach, 21, of Savannah, Catherine M. Pittman, 21, of Alpharetta and Caitlyn N. Baggett, 21, of Millen.

Hospital officials said they were wrapping up clinical training for the year.

"You could tell they really loved what they did," Sherry Danello, the hospital’s chief nursing officer, said in a statement. "They didn’t just go through the task, they really connected to the patients."

The crash halted some motorists for more than six hours as road crews and tow trucks cleared the wreckage. Even when traffic began moving again, troopers kept a 6-mile stretch of eastbound I-16 closed as they investigated.

Nease said the driver of the tractor-trailer had not been cited as investigators worked to determine exactly what happened. The driver’s name was not immediately released. State troopers said weather didn’t seem to be a factor.

"There was no fog or smoke. It was clear as a bell," said Sgt. Chris Rodewolt of the State Patrol. "We did have heavy, heavy traffic."

Two mangled passenger vehicles rested Wednesday at the bottom of an embankment beside the interstate. In front of them, just off the highway, was a tractor-trailer with its cab smashed into the back of a tanker truck.