A school bus crash near the southern Arizona city of Tucson has left several students from a different part of the state seriously injured and closed a major interstate. The Arizona Department of Transportation told USA TODAY that Interstate 10 was closed in both directions around milepost 240 in Marana and that "there is no estimated time to reopen the highway.

Large school buses are built to not need seatbelts. Instead, they're designed for compartmentalization, a concept that protects impact. Arizona is one of the many states that doesn't require them.

Two people had to be taken to the hospital, but are expected to be OK.