An unidentified witness told WSBT-TV, South Bend, the buses, which were carrying about 100 students, were traveling on State Road 13 in North Webster about 3:30 p.m. when the fourth bus slammed into the third one, triggering the chain reaction.
The witness said the Wawasee buses were carrying middle and high school students.
A Kosciusko Community Hospital representative told the TV station 46 patients were being treated there, including a bus driver who was airlifted. The representative said none of the victims was in critical condition.
Four other children were taken to another hospital where a representative said they were treated and released, WSBT-TV said.
Students who were not hurt were taken by another bus to Wawasee Middle School where they were picked up by their parents, police said.
Stacey Page Online, a Kosciusko County online newspaper, reported John Wagner, the driver of the fourth bus who was airlifted to the hospital, had abdominal injuries. The driver of the third bus, Julie Close, had minor injuries, the newspaper said.
No injuries were reported for the other two drivers, identified as Cyndi Routh and Dave Granger.
North Webster Fire Chief Jeremy Likens said it was the worst school bus accident in his 21 years with the department.
"Once the command post and triage was set up, everybody did a fantastic job," Likens stated.
Penelope Cruz named 2013's 'Best Body' by Fitness magazine
Susan Sarandon: I was stoned at almost every awards show