ZAGREB, Croatia — At least eight Czech tourists were killed and 44 injured when a bus crashed and overturned on a major highway in Croatia on Saturday, police said.

The accident happened around 4 a.m. about 200 kilometers (125 miles) south of Zagreb, on a highway connecting the Croatian capital with the central Adriatic coastal city of Split, according to a police statement.

Croatia's state TV said the bus crashed through metal barriers in the middle of the highway, and overturned in the opposite lane near a tunnel.

State TV quoted eyewitnesses as saying the bus started "swaying" moments before the crash, suggesting the driver apparently lost control after he fell asleep.

Photos from the scene showed the bus's twisted metal remains on its side, with seven dead passengers – covered with white sheets – lying on the pavement. State TV said a child was among the dead and the eighth fatality was discovered in the wreckage.

Most of the injured passengers were hospitalized in the nearby town of Gospic, while three of the most seriously hurt, including two children, were flown to Zagreb by a helicopter.

Hospital Dr. Marija Vrkljan Ilijevska told Croatian TV that those hospitalized in Gospic were not seriously injured, mostly with fractures and concussions.

The highway was temporarily closed for traffic, and the cause of the accident was under investigation.

Czech Prime Minister Petr Necas called the crash "a huge tragedy" and offered condolences to the families of the victims. He said in a statement Czech authorities are doing all they can to help.

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  • Wreckage is strewn at the scene of the bus crash near Gospic, Croatia, Saturday, June 23, 2012. At least eight Czech tourists were killed and 44 injured in a bus crash on a major highway in Croatia early Saturday. The accident happened around 4 a.m. about 200 kilometers (124 miles) south of Zagreb, on a highway connecting the Croatian capital with the central Adriatic coastal city of Split, according to a police statement. Croatia's state TV said the bus crashed through metal barriers in the middle of the highway, and overturned in the opposite lane near a tunnel. (AP Photo/Darko Bandic)

  • A police officer takes photographs of the bus crash near Gospic, Croatia, Saturday, June 23, 2012. (AP Photo/Darko Bandic)

  • Police survey the scene of the bus crash near Gospic, Croatia, Saturday, June 23, 2012. (AP Photo/Darko Bandic)

  • Wreckage is seen at the scene of a bus crash near Gospic, Croatia, Saturday, June 23, 2012. (AP Photo/Darko Bandic)

  • An aerial view of the scene of the bus crash near Gospic, Croatia, Saturday, June 23, 2012. (AP Photo)

  • Police and firefighters survey the scene of the bus crash near Gospic, Croatia, Saturday, June 23, 2012. (AP Photo)

  • Police survey the scene of the bus crash near Gospic, Croatia, Saturday, June 23, 2012. (AP Photo)