A 16-year-old boy driving his parents and siblings on a "dream trip" to Disney World apparently fell asleep at the wheel, causing the sport utility vehicle to veer off the highway and roll over, killing three children and two adults, authorities said Thursday.

The teen, who had a driver's license, was cited with careless operation, a misdemeanor, following the crash on Interstate 20 near Calhoun, Louisiana, at 11 p.m. Wednesday, said state police spokesman Michael Reichardt. The driver, who was not identified, and two passengers were injured, one critically.

While en route to Orlando, Florida, from Terrell, Texas, the 16-year-old veered left onto the median and then tried to get back onto the highway but overcorrected, causing the 2005 Chevrolet Tahoe to roll over, police said.

Authorities identified the adults killed as Michael Hardman and his wife, Trudi Hardman, both primary-school teachers from Terrell, Texas, and three of their children: sons Dakota Watson, 15, and Adam Hardman, 7; and daughter Kaci Hardman, 4.

None of those killed wore seat belts but the driver did, officials said.

The distance between Terrell and Orlando is about 1,050 miles -- a 16-hour drive. The family left their home in Terrell about 7 p.m. or 8 p.m. Wednesday, said Michael Hardman's brother, Timothy Hardman, meaning the accident occurred early in the journey.

Michael Hardman was a second-grade teacher at an elementary school in Terrell, said Terrell Independent School District Superintendent Michael French. He had worked in the district for two years, French said.

Hardman also was a little league baseball coach who coached his sons, one of whom, 12-year-old Aaron Hardman, was in critical condition at a Shreveport hospital, Timothy Hardman said.

"He never turned a kid away," Timothy Hardman said. "Michael probably had the biggest heart of anybody you ever knew. He just loved kids."

The driver and the other injured passenger were treated at the hospital and released Thursday morning, Hardman said.

French said a counselor contacted the parents of students in Michael Hardman's class to let them know about his death, and counselors also are available to support both staff and students.

"Our thoughts and prayers are with his family members, colleagues, students and friends," he said. "We must lift each other up during this difficult time," French said.

Trudi Hardman was a kindergarten teacher at Wills Point Primary school, and had worked for the Wills Point Independent School District for about 10 years, Superintendent Suzanne Blasingame said in an e-mail.

Blasingame said Michael Hardman also had formerly taught at Wills Point Primary.

"Our school and community is grieving for this family," said Blasingame, who had traveled to Louisiana to be with the family.

Timothy Hardman, 38, of Crandall, Texas, said his brother and Trudi Hardman were married about five years ago and had six children between them. Michael Hardman had three boys from a previous marriage, while Trudi Hardman had two boys from a previous marriage, Timothy Hardman said. The couple had a daughter, Kaci, together, he said.

Timothy Hardman, who traveled to Louisiana after he was notified of the accident, said his brother's family had scheduled the trip about nine months ago, and had planned to stay at Disney World for a week.

"They've always talked about it," he said. "It was their dream trip. It was an opportunity for them to take all of their kids."

Police don't believe the young driver was impaired, but a toxicology sample was taken. The stretch of I-20 where the deadly crash took place is flat and straight and the weather was clear, they said.

"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."