The bus driver faces criminal charges.
Of 37 patients admitted to the Karlovac hospital upon the accident on Tuesday evening, four children and two teachers have remained in the hospital.
One of the injured teachers had a part of her forearm amputated.
The bus, carrying 44 third-graders from Prigorje Brdovecko near Zapresic, was on its way back from the Plitvice Lakes national park.
Last Thursday, a bus with 52 teenagers travelling along the Zagreb-Karlovac highway broke through the fence separating highway lanes, crossed the lanes running in the opposite direction and landed in the nearby field. Forty-seven persons were injured in that accident. It was established that the driver was not under the influence of alcohol but it is still not known why he lost control of the vehicle.