VICTORIA -- Four people from Vancouver Island are facing multiple charges of human trafficking after they were arrested in a convoy speeding across southern Saskatchewan.

Mounties in Saskatchewan say an off-duty officer saw three vehicles with tinted windows speeding along the Trans-Canada Highway in close proximity Tuesday.

Mounties were issuing tickets to the drivers for travelling in excess of 153 km/h when they noticed two young girls in the back seats of the vehicles.

The girls, who are under 18, are from B.C. and did not have identification, according to police.

Victoria residents Shawn Alexander Kelly, 23, and Shermineh Sheri Zaiee, 36, were arrested, along with Nanaimo residents Seyed Kamran Miralinaghi, 19, and Seyed Kourosh Miralinaghi, 19.

The three men and one woman are all facing multiple charges, including transporting a person under 18 for the purpose of exploitation; procuring a person to offer or provide sexual services; and knowingly advertising to provide sexual services.

All four are scheduled to appear in court in Swift Current, Sask., on Jan. 31.

The RCMP says the two girls aren't related to the accused and their names will not be released.