Jamison and Kathryne Pals and their children, left to right: Ezra, Violet and Calvin. The vice president of a local nonprofit called the couple, "the most selfless people you would ever want to meet." (Star Tribune/The Minnesota Star Tribune)

A big rig truck driver was charged Tuesday in a western Nebraska court with rear-ending a van and killing a Twin Cities family of five that was about to move to Japan to work as Christian missionaries.

Tony A. Weekly, 53, of Baker, Fla., was charged with motor vehicle homicide and reckless driving in the multivehicle crash just before noon Sunday on Interstate 80 in a construction zone near Brule.

Jamison and Kathryne Pals, both 29, died along with their children when the semitrailer truck rear-ended their minivan. Also dead at the scene were their children: Ezra, 3; Violet, 23 months; and Calvin, 2 months. Another person in the five-vehicle pileup also died, according to court documents.

Weekly was treated at the Sedgewick County Hospital in Julesburg, Colo., and released. He was then jailed in Ogallala ahead of appearing in a Keith County courtroom late Tuesday afternoon.

Law enforcement has yet to disclose what may have led Weekly to hit the Pals' vehicle from behind.

Kathy Pals, Jamison's mother, said Monday that she'd been told by authorities that Weekly had been distracted before the crash.

The allegations filed Tuesday in court against Weekly described him as "inattentive and distracted by outside influences" in the moments after the crash. Weekly had a blood sample taken for testing while at the hospital. He also gave a statement to authorities, the court filing read.

Witnesses said that Weekly's semi was speeding in the construction zone and didn't slow down before impact, according to the filing. The force pushed the family's van into three other westbound vehicles. Both the van and the truck burst into flames.

Six people in the three other vehicles were initially transported to the Ogallala Community Hospital for a range of injuries. Three were transferred to hospitals in Colorado for further treatment. Authorities have not disclosed which of those six later died.

The Palses, of Minneapolis, met at the University of Northwestern-St. Paul, an evangelical Christian college in Roseville, and in recent months had sold most of their belongings in preparation for the move, which was expected to happen in late October.

The young family had been planning the move for a couple of years and made multiple treks to Littleton, Colo., for training with WorldVenture, a Christian mission agency. They tracked their preparations on a blog called joyofjapan.org, where they wrote expansively about their faith and family.