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.

Three high school students and one adult suffered serious injuries when their school bus crashed in Tucson, Arizona, on Tuesday.

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