CALHOUN (AP) — Three children and two adults from an East Texas family were killed on their way to a Disney World vacation when their sport utility vehicle veered off the interstate and rolled over in northeast Louisiana, police said.

The car was driven by a 16-year-old who likely fell asleep at the wheel just before 11 p.m. Wednesday on Interstate 20 near Calhoun, state police spokesman Michael Reichardt said. The driver and two additional passengers suffered minor injuries.

Authorities identified the adults killed as Michael and Trudi Hardman of Terrell, Texas. The children killed were ages 4, 7 and 15. None of those killed wore seat belts but the driver did, officials said.

Troopers said the 16-year-old drove left into the median and then tried to get back onto the highway but overcorrected, causing the 2005 Chevrolet Tahoe to roll over.

Troopers say six of the eight people in the SUV were thrown from the vehicle. Ouachita Parish coroners pronounced the five family members dead on the scene.

“Our heartfelt condolences go out to all of the people affected by this tragic crash,” said Col. Mike Edmonson, the Louisiana State Police superintendent. “In an instance this family vacation turned into an unspeakable tragedy.”

Troopers said they did not suspect the young driver was impaired, but a toxicology sample was taken.