At least seven Czech tourists were killed and 44 injured in a bus crash on a major highway in Croatia early Saturday, police said, according to the AP.

The accident happened at around 4 a.m. some 200 kilometers (124 miles) south of Zagreb, on the highway connecting the Croatian capital with the central Adriatic coastal city of Split.

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

The TV quoted eyewitnesses saying that the bus started "swaying" on the highway moments before it crashed through the barriers.

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

Gospic General Hospital doctor Marija Vrkljan Ilijevska told the Croatian TV that those hospitalized there were not seriously injured, mostly having fractures of extremities and concussions.

The highway was closed for traffic because of the crash. The cause of the accident was under investigation.