A head-on collision between a minibus and a semi-truck early Wednesday morning has left 23 people dead and five others injured in the southern Brazilian state of Parana.

According to the Federal Highway Police, among the dead were two children, as well as the semi-truck driver. A preliminary investigation showed that the semi-truck veered into the oncoming traffic and struck the minibus, which was transporting local patients to hospitals in the Greater Curitiba area.

Local authorities said that three of the injured remained in serious condition.

In response to the tragedy, Parana Governor Ratinho Junior declared three days of official mourning across the state.