Police in York Region are growing increasingly concerned for the wellbeing of a missing 17-year-old girl and have stepped up their efforts to locate her.

Shu Tong was last seen on Monday shortly before 9:30 a.m. walking northbound on Yonge Street, on the east side of the street, near Devonsleigh Boulevard, which is just south of 19th Avenue in Richmond Hill.

She is described as female, 17-years-old, Asian, five-foot-three, and 120 pounds with brown eyes and long black straight hair in a ponytail.

At the time of her disappearance, Shu was wearing a black hooded sweater, blue cargo pants, and light grey sneakers.

York Regional Police (YRP) say she hasn’t been in contact with her family for more than 24 hours.

Speaking with reporters on Tuesday morning, Stf. Sgt. Jason Hayes, of York Regional Police, said it is “unusual” for Shu to not be in touch with her relatives for that length of time.

“The fact that she hasn’t communicated with her family for over 24 hours is certainly out of character, and that’s part of why we are concerned for her wellbeing,” he said, adding they’re considering Shu a “vulnerable person.”

Hayes said the force’s search and rescue team is working to determine her direction of travel and if she is still in the area.

“We have also had our Canine Unit, as well as our Air Support Unit, assisting with that search,” he noted.

A command post has been set up in the parking lot of a church at 12125 Yonge St., near Stouffville Road, and people can expect to see a large police presence as investigators canvass that area.

Police are also appealing to anyone that was driving in that area between 9:15 and 9:45 a.m. to check their dashcam footage.

At this time, criminality is not a factor in this investigation, Hayes said.

Anyone with further information is asked to contact YRP’s #2 District Criminal Investigations Bureau at 1-866-876-5423, ext. 7241, or Crime Stoppers anonymously.