"First and foremost, no children were hurt, and that's the No. 1 priority here," said Lt. Mark Peterson of the Minnesota State Patrol.
Peterson was summing up the feeling of grateful relief shared by administrators at The International School of Minnesota in Eden Prairie. It's a private, college preparatory school with 550 students.
Eleven of them were on the bus Tuesday morning, taking one of four bus routes to school.
State Trooper Mark Peterson says the roads were somewhat slick as the bus approached 494. On the entry ramp, it tipped over.
"The bus did the job it was designed to do. They're constructed to absorb crashes if they unfortunately do happen, and that's what happened in this case," said Peterson. "Were they wearing seatbelts? No, they weren't. The bus rolled onto its side. And again, because of its construction, the children escaped injury, using the emergency hatches to exit the vehicle."
The driver, Glenn Miller, 73, was not injured either.
Hennepin County Medical Center sent an ambulance, and medical staff checked out the children.
"It's my understanding that the vast majority of them fit inside the ambulance, so they were able to stay warm, until another bus could come," said Peterson. "Obviously we don't want them running around on the freeway, so we put them inside the ambulance to keep them in one spot, keep them warm, keep them safe."
One of the older students called 911, and others used their cell phones to call their parents. School Director Sue Berg says they were all in class by about 9:30. "None of them went home. All of them are back in class, and really seem to be very -- you know how kids are -- very confident, and I think the atmosphere of school is calm," said Berg. "Most of the parents actually came here to school to see their children, and obviously they were involved in the decision of the kids' staying and going right to class. "
Safety experts say school buses are the safest way for kids to get to school. Mike Martin, executive director of the National Association for Pupil Transportation, says drivers are well-trained and regularly tested for drugs and alcohol.
Buses keep the students high above the point where cars and small trucks would hit them. And the seats are designed to protect the riders, in a system called compartmentalization.
"They're high-backed, closely spaced, securely anchored, well padded, energy-absorbing seats, that are actually designed to absorb the impacts in a crash," said Martin.
Even if the bus rolls onto its side, as it did Tuesday, Martin says the seats can keep the children in place and protected long enough for the bus to slow way down, and give them a fairly gentle landing.
"The federal government and crash test experts have said repeatedly that a school bus is the safest form of ground transportation in America. There is no safer way for a student to travel to and from school," said Martin. "In fact, kids who ride a school bus are at least eight times safer than children who ride to school with their parents in their own passenger cars."
The State Patrol is investigating the accident, and will interview the driver, talk to witnesses, inspect the bus and its maintenance records. It could be as long as a month before the report is ready.