A 42-year-old Ontario man has been arrested in Calgary following a human trafficking investigation, with police warning there may be additional victims.Mark Williams, of Scarborough, Ontario, was arrested Friday in Calgary's Sunridge neighbourhood following a joint investigation by Alberta Law Enforcement Response Teams (ALERT) and the Calgary Police Service.Williams has been charged with one count of procuring a person for sexual services.Investigators allege Williams was involved in the sex trafficking of a vulnerable woman in Calgary.Police said the investigation began after authorities received information about a suspected sex trafficker operating in the city.“We received a tip about a known sex trafficker operating in the Calgary area,” said ALERT Staff Sgt. Matt Pumphrey.“We were able to gather intelligence, conduct an investigation, and quickly make an arrest.”ALERT has not disclosed how long Williams was allegedly operating in Calgary or whether the investigation involves other locations.Investigators believe there could be additional victims connected to the case and are appealing to the public for information.The woman identified during the investigation has been provided assistance through ALERT's Safety Network Coordinators, who help connect human trafficking survivors with support services..Police are reminding victims and survivors of human trafficking that assistance is available by calling 211.Williams remains in custody and is scheduled to appear in court on Thursday.ALERT is asking anyone with information about Williams or potential additional victims to contact their local police service.Anonymous tips can also be submitted to Crime Stoppers at 1-800-222-8477.ALERT is a provincially funded law enforcement organization that brings together specialized police resources to investigate serious and organized crime across Alberta.The organization works with municipal police services and the RCMP to target criminal networks involved in activities including human trafficking, drug trafficking and organized crime.