Zealandia is about 95 kilometres southwest of Saskatoon. ((CBC))

A 17-year-old youth is dead, and a 20-year-old woman is in critical condition following a highway accident in west-central Saskatchewan on Friday.

The accident involving a car and a semi-trailer happened around 8:15 a.m. between Harris and Zealandia on Highway 7.

The teen was a passenger in the car and the woman was the driver. It slammed head-on into the semi-trailer, the RCMP said.

Just before the crash, a second car had been in the wrong lane, trying to pass a semi.

To avoid the oncoming vehicle, the first car steered onto the shoulder, but then lost control and smashed into the big truck.

An accident reconstruction expert was called in and the highway was closed down to just one lane until late Friday Afternoon.

Police said the youth who died was Benard Huckabay of Flaxcome, Sask., a community 130 kilometres west of Zealandia. 

Police are asking for the public's help in finding the car that passed the semi in the first place.

The driver kept going, the RCMP said.