A prison bus carrying 21 residents of the Topeka Correctional Facility on a work program in southeast Kansas collided with a semi-truck early Thursday, a spokesman for the Kansas Department of Corrections said in a release.

Nine people, including eight residents of the women’s prison, were injured during the crash, said David Thompson, a spokesman for the corrections department. Three of the women had broken bones. All eight were expected to recover.

The bus driver was seriously injured and taken to a Kansas City area hospital. Meanwhile, the 13 other residents of the prison who were not injured were taken back to the worksite and then sent to a hospital to be checked out as a precaution.

The prison bus and semi crashed shortly before 1 a.m. at U.S. 169 and Oregon Road just outside of Iola in Allen County, a Kansas Highway Patrol dispatcher said.

The residents had just finished their 3 to 11 p.m. shift at the Russell Stover plant in Iola, Kansas, and were returning to Topeka.

According to the preliminary investigation, the prison bus was headed east on Oregon Road when it failed to stop at a stop sign and started to turn onto the highway, the dispatcher said.

The semi, which was headed south on U.S. 169, swerved to avoid the crash. The prison bus, however, collided with the semi on the passenger side, the dispatcher said. The collision caused the semi to roll into the ditch.

The corrections department is working with the highway patrol to determine the cause of the crash.

The Topeka Correctional Facility is the state’s only prison for adult women. It currently has a population of 762 women.