Police officers said that Shepherd ignored the bus's lights and stop arm and tried to speed past the vehicle when she hit the children.
Indiana State Police say the children were hit by a auto as they crossed the street to board the bus, which had its stop arm down.
The "three handsome kids", identified by Indiana State Police as twin brothers Xzavier and Mason Ingle, 6, and their older sister, Alivia Stahl, 9, were "taken for no reason", he said.
Slocum says the injured boy, Maverik Lowe, was airlifted to a Fort Wayne hospital in serious condition.
Shepherd was arrested at her workplace in Rochester on October 30 at around 4 p.m. and was released later Tuesday on a $15,000 bond.
"You're suppose to be able to go to your bus stop and be safe, you're suppose to get on your bus and be safe".More news: Tesla Model 3 production reportedly being investigated by the Federal Bureau of Investigation
Police are interviewing a woman who was driving the vehicle involved. The bus had the stop arm down at the time, but the pickup truck who hit the four children failed to stop.
Authorities do not believe alcohol was a factor in the crash. "There are no words", she said. We have learned of three student fatalities and one student seriously injured and airlifted to a Fort Wayne hospital as they were hit by a truck while boarding their bus.
The rural Rochester residents were students at nearby Mentone Elementary School.
Family said they previously reached out to say it's not safe for kids to cross the highway, especially at the time of the morning when it's still dark. "They had a future", Ingle told ABC News. "He lost all his kids", Ingle said.
'What do you tell your little brother, how do you tell your little brother it's gonna get better? "You can't. My brother, the most loving man in the world and the best father I've ever known, now is a father to no one".
School district officials said school counselors will be working closely with students, parents and staff as they try to process the loss. He said parents complained that it was unsafe for children to cross a highway where vehicles routinely travel at 50 to 60 miles per hour.