ROCHESTER, Ind. (AP) — The National Transportation Safety Board says a northern Indiana school district is partially to blame for a 2018 crash that killed three siblings crossing a rural highway to reach their stopped school bus.

The NTSB said Tuesday the crash near Rochester was caused by a pickup truck driver’s failure to stop for the school bus, despite its activated and clearly visible warning lights and stop arm.

In February, the driver, Alyssa Shepherd was given a sentence of four years in prison for hitting and killing the children and injuring another.

However, it says contributing to the crash was the Tippecanoe Valley School Corp.’s inadequate safety assessment of school bus routes.

That resulted in a prevalence of bus stops that required students to cross high-speed roadways to board a bus.