(CNN) -- A Kentucky pastor said it was "easier" that a Mennonite couple that was engaged to be married died together in a car crash Friday instead of one having to live without the other.
"I'm just thankful that not one of them was left behind. It would be so much easier for them this way, both being able to go, be together in heaven," Leroy Kauffman, pastor of the Marrowbone Christian Brotherhood Church in Burkesville, said in a press conference Friday.
The two were among 11 people killed in a fiery crash Friday morning after a tractor-trailer crossed a median and smashed head-on into a van in what is being called Kentucky's deadliest vehicle wreck in 20 years.
The driver of the tractor-trailer, which was operated by Hester Inc., from Fayette, Alabama, was killed, a spokesman for the National Transportation Safety Board said Friday.
The passengers in the 15-person van were Mennonites traveling to a wedding in Iowa, Kauffman said. Nine of them were congregants in his church.
"It's been a tremendous shock," he told reporters later. "At the same time, we're experiencing the grace and peace of God."
Mennonites and Amish trace their roots to the same Anabaptist movement and share some of the same beliefs concerning baptism, non-resistance, and basic Bible doctrines. They differ in dress, technology, language, form of worship, and interpretation of the Bible, according to Third Way Cafe, a Web site run by the Mennonite Missionary Network.
John Eshe, a fellow minister in the church and his wife, Sadie, were killed, Kauffman said. So were four of the couple's 12 children; a daughter-in-law, a baby grandson and their daughter's fiance, Kauffman said. CNN affiliate WBKO reported that the 10th person in the van was a friend of the family.
Two children, ages 3 and 5, survived, Kauffman said. They were adopted from Guatemala by the Eshes' eldest son, Leroy, and his wife, who were both killed, Kauffman said. The couple's third adopted child, a baby who was likely held by someone in the car when the crash occurred, was killed, Kauffman said.
The surviving boys are with their mother's parents, the pastor said. A trucker who came upon the scene found the two of them alive and put them in his truck, where they fell asleep, he said, and they were "kept warm" there until the officials arrived.
"They're very sweet, very intelligent little boys," he said.
The family was "mission-minded," the pastor said, explaining that two of the couple's other children are missionaries in Brazil, and a son, Johnny, died on a mission trip to the Ukraine three years ago, he said.
"You can see that John's heart was to have his children in the work of the Lord," Kauffman said.
The NTSB will begin an investigation into the wreck Saturday morning, spokesman Peter Knudson said.
"It's so early in the investigation, so we've ruled nothing out, but we do know the tractor-trailer did leave the roadway and crossed the barrier. We do know that happened, we don't know why it occurred," he said. "We've got a lot of work to do."
The wreck happened between 5:30 a.m. and 6 a.m. at mile marker 63 on Interstate 65, roughly 40 miles northwest of Bowling Green, near Mammoth Cave National Park, said Lt. David Jude, a spokesman for the Kentucky State Police.
Authorities briefly closed the southbound lanes of Interstate-65 so medical helicopters could land, but those lanes soon reopened. The northbound lanes remained closed early Friday afternoon, Jude said.
Kentucky Gov. Steve Beshear offered his condolences. He said his office was in contact with emergency personnel and will follow the investigation.
"Today and the days that follow will be very difficult for these families and the surrounding community," he said. "Our entire state grieves with the community and all the families will remain in our thoughts and prayers."
Meanwhile, members of the tight-knit Mennonite community where most of the victims came from were trying to come to terms with the deaths.
"Life will go on, but it'll be difficult," said Kai Steinmann, a neighbor and friend of the Eshes. "For us as a community, I think it's going to mean that a big piece of us is gone."
Steinmann, 25, described the Mennonite community as a "largely construction-oriented" group of about 100 people that formed 10 years ago.
The night before the accident, Steinmann said the Eshe family attended a church meeting with other members of the community, expressing excitement over the wedding and requesting prayers for safe travel.
"We will accept it as the will of God," Steinmann said. "This isn't an accident, God knew this from the beginning and that will be one of the beginning things that the community will do, accept it as the will of God."
The CNN Wire Staff contributed to this report.