Nine people, including five women, were killed and 19 others injured after an express bus overturned at Km146 of the North-South Expressway near Tangkak early Sunday.
However, the identities of the dead, including the driver and co-driver, have yet to be ascertained.
Muar police chief ACP Nasir Mohd Ali said the bus was carrying 28 people, including the driver and co-driver, when the accident occurred at about 2am when it was travelling from Ipoh to Johor Baru.
The injured passengers and the nine bodies have been taken to the Sultanah Fatimah Specialist Hospital in Muar.
Initial investigation revealed that the driver lost control of the vehicle and it skidded and overturned, jolting the passengers out of their sleep.
The police and Fire and Rescue personnel took about an hour to remove the body of the driver who was pinned to his badly crushed seat.
Nasir is scheduled to give further details of the accident at a news conference later Sunday.