VANCOUVER Police say they are in a race against time to locate a missing Vancouver senior who they believe went for a walk in South Burnaby on Friday night and hasn t returned. The Vancouver Police Department announced that it was looking for 68-year-old Thomas Tremblay in a news release Friday night. On Saturday, it followed up with an urgent appeal for help, saying the missing senior likely spent the night in sub-freezing cold. Coquitlam Search and Rescue tweeted around 1:15 p.m. Saturday that it had been activated to search for Tremblay in Burnaby. Jim Delgrande, search manager for Coquitlam Search and Rescue, told CTV News Vancouver the group was called out around 12:30 p.m. Saturday and would continue searching at least until dark in and around Byrne Creek Park in South Burnaby.