The crash happened at around 6:45 a.m. in a remote area of St. Francois County, about 80 miles (130 kilometers) southwest of St. Louis, the Highway Patrol said.
The Mennonite family was on the way to pick blueberries at a nearby farm near when the truck slammed into the back of their carriage, patrol Cpl. Juston Wheetley told the St. Louis Post-Dispatch.
"The truck went over the top of it. It's literally destroyed," he said of the carriage.
The 8-year-old died at the scene. The other two children, ages 10 and 12, were taken to St. Louis Children's Hospital with serious injuries. The injured adults, ages 50 and 28, were also seriously hurt and were taken to Barnes-Jewish Hospital, authorities said. The 19-year-old driver of the carriage wasn't injured. Authorities haven't released the names of those involved in the crash.
The 19-year-old pickup truck's driver and his passenger were not hurt, and the driver stayed at the scene and cooperated with police, Wheetley said. He said the crash happened on a straight stretch of the two-lane highway and that the carriage had an orange safety placard attached, adding that it isn't clear how fast the truck was going.
The county's Mennonite community was established just two years ago, the Post-Dispatch reported.
Wheetley said Mennonite and Amish carriages have previously been struck by motorized vehicles in Missouri, but that Thursday's crash was the most "severe" he was aware of in that area.
There have been other similar fatal wrecks in recent years, including last month in Algansee Township in southern Michigan, when a pickup truck slammed into a horse-drawn carriage, killing three young Amish children and seriously injuring one other and their mother. The 21-year-old pickup truck's driver was charged with drunken driving causing death and serious injury.
In October of 2017, a truck crashed into a buggy near Sheridan, Michigan, killing three children whose family was on its way to a Sunday service. The 29-year-old truck driver pleaded guilty to misdemeanor moving violation charges.
Information from: St. Louis Post-Dispatch, http://www.stltoday.com
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