The crash happened around 8:35 a.m. in the northbound lanes on the I-55 Smith Bridge, which crosses the Des Plaines River in Channahon, police said.
The three school buses were heading north in the right lane as traffic slowed to a stop, police said.
State police said the driver in back didn't stop in time, and struck the bus in front of it, triggering a chain-reaction crash involving all three school buses.
"Our drivers did a nice job notifying us of the accident and we all went into action," said Mark Mitchell, superintendent of Reed Custer School District 255. "I took one of our district vehicles, I was able to go up the frontage road, I was able to sneak up the interstate to get to where the accident occurred."
Mitchell said 10 students and two teachers were taken to local hospitals to get treatment for minor injuries.
"I feel bad for our students, I feel bad for our drivers. Our drivers do an amazing job day in and day out, and again the fact that we walked away with very minor injuries, I'm just very grateful for that," he said.
Mitchell said school administrators sent four messages to parents and guardians after the crash. Extra buses were sent to bring the students back to Reed Custer Middle School.
Braidwood Police Chief Bret Goodwin said he called in all available officers to assist in reuniting students with their parents at the school.
Around 10:30 a.m. tow trucks were seen moving the school buses off the Smith Bridge on I-55.
Traffic was backed up for a couple of miles, and the right lane of I-55 was temporarily closed on the bridge Tuesday morning, police said.
The students were on their way to the traditional eighth grade Six Flags field trip, and while it didn't happen, all kids and adults are expected to be OK.
The school bus driver that crashed first was cited for failure to reduce speed to avoid a crash.
No other vehicles were involved in the crash. All lanes were re-opened by 12:30 p.m.
Illinois State Police is investigating the crash. Administrators are looking at options to reschedule the trip, as the eighth graders' last day of school in Wednesday. They are considering a fall trip, when the students begin their first year of high school.