Three children from the same family were killed and a fourth child was seriously injured Tuesday morning when they were struck by a pickup truck as they were about to board a school bus, police said.
Identical twin 6-year-old brothers, Xzavier and Mason Ingle, and their 9-year-old sister Alivia Stahl were killed in the incident on a rural road in Indiana, said Sgt. Tony Slocum, the public information officer for the Indiana State Police.
An 11-year-old boy, Maverik Lowe, suffered multiple broken bones, said Slocum.
The driver of the pickup truck, Alyssa Shepherd, 24, taken into custody Tuesday afternoon and charged with three counts of reckless homicide, and one misdemeanor count of disregarding a stop sign and causing injury, officials told ABC News. Shepherd was taken to the Fulton County Jail but was released Tuesday night on a $15,000 surety bond, evening jail supervising officer Adam Roop told ABC News.
The incident occurred around 7:15 a.m. in Rochester, a city near Fort Wayne, Slocum told reporters at the scene. The injured boy was taken to Parkview Hospital in Fort Wayne by helicopter and was undergoing surgery, Slocum said.
The twins' father came to the scene and identified his children, Slocum said.
"Our hearts just break for the families involved here in this tragic situation, and our prayers obviously go out to them," Slocum said. "It was a tough day to watch the emotions that these family members had to go through and a tough day for first responders. It's been a while since I've seen first responders cry, but I saw some tears shed today because that's what the situation dictated."
The four children were crossing a two-lane road from a mobile home park where they lived to get to their school bus when they were struck by a Toyota Tacoma truck, police said. A preliminary investigation showed the yellow school bus was in the northbound lane of State Road 25 with its emergency lights flashing and its stop-sign arm out when the children were struck by the southbound truck, Slocum said.
Shepherd of Rochester stayed at the scene and has been cooperating with police, said Slocum.
The NTSB has launched a "go team" of investigators to look into the crash. More than six federal investigators will arrive in Rochester Wednesday to find out how the children were killed, an NTSB spokesperson told ABC News.
The agency will zero in on how to keep children safe while embarking and disembarking a school bus, officials said.
All of the children attended Mentone Elementary school in nearby Mentone, Indiana, where Alivia made the honor roll in January.
Slocum said the Shepherd submitted to a blood test to determine if drugs or alcohol were involved. He said investigators interviewed her, but he declined to disclose what she said about the crash.
"We don't know why this crash happened as we speak here right now," Slocum said.
Aerial photos from ABC affiliate WLS-TV in Chicago showed a pickup truck with heavy front-end damage at the scene.
The Tippecanoe Valley School Corporation posted a statement on Facebook after the incident.
"Our school corporation has suffered a tragedy this morning. 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 vehicle while boarding their bus. We have deployed all school counselors to meet the emotional needs of our staff, students and parents," the school wrote on Facebook. "We are awaiting to learn more confirmed details but wish to ask the community to come together to pray for the families, our students and our staff."
ABC News' Jeffrey Cook and Darren Reynolds contributed to this report.