Seven people, including a six-year-old and 16-year-old, were killed when a bus overturned in the US state of Mississippi early Saturday, Warren County Coroner Doug Huskey said.

The two young victims were siblings, according to the coroner.

The Mississippi Highway Patrol said the incident took place around 12:40am on Interstate 20 near Bovina in Warren County, east of Vicksburg, when a 2018 Volvo commercial passenger bus traveling westbound left the roadway and overturned.

Thirty-seven passengers were transported to different hospitals with unknown injuries, the agency said. It said the co-driver was not transported.

"Anytime you have people injured or killed, it's tragic but when you have a situation like this where you have multiple fatalities and multiple injuries, it makes it even worse," Warren County Sheriff Martin Pace told an ABC affiliate.

Huskey said most of the passengers on the bus were Latin American. (Reuters)