An early morning accident sent four high school students to the hospital Wednesday with minor injuries, school district officials said.

The students were on their way to Rio Grande City High School just before 8 a.m., when the school bus they were riding in was rear-ended by an 18-wheeler, said school district spokeswoman Cynthia Ybarra.

The collision occurred as the bus was stopped in front of railroad tracks near the intersection of Expressway 83 and Farm-to-Market Road 1430.

The students are expected to recover from their injuries, Ybarra said. All other passengers on the bus were taken to Starr County Memorial Hospital as a precaution.