GALESBURG, Ill. — Elementary school students had a frightening ride back from a field trip on Thursday when strong winds blew out a portion of their bus’ windshield.

Officials told The Register-Mail that the passenger side of the windshield shattered as the bus was heading directly into heavy winds north of Galesburg. The driver’s side of the windshield stayed in place, allowing the driver to slow down and bring the bus to a stop on the shoulder of an interstate.

Four of 30 fourth-graders on the bus sustained injuries and were transported to a hospital for treatment. Gene Denisar, the superintendent of the district where the students attend school, told the newspaper that doctors placed four staples in one student’s scalp; another suffered a possible eye laceration; the third student had a possible head injury, but X-rays turned up negative; and the fourth student suffered minor facial lacerations.

“An investigation into the windshield should certainly happen,” Denisar said. “It’s supposed to be shatterproof. But thank goodness it wasn’t worse.”

National Weather Service officials reported that winds reached 38 mph in Galesburg and 45-55 mph elsewhere in Illinois on Thursday.