York Regional Police are trying to speak to people who saw Const. Garrett Styles in the moments leading up to the officer's death Tuesday to fill in the timeline of events.

Police stepped up the interview process Wednesday morning by canvassing the stretch of Highway 48 where Styles died during a traffic stop.

Officers stopped vehicles to speak to those who regularly drive along that stretch of highway, located east of Newmarket in East Gwillimbury, between 4:30 a.m. and 5 a.m.

Investigators want to speak to anyone who saw Styles, especially while his vehicle was stopped on the side of the road with a minivan or while he was interacting with the occupants of the van, said York police Insp. Gary Miner.

"We're trying to locate people that may have seen (Styles) stop the vehicle to fill in our timeline in the investigation," Miner said.

Police also want to speak to people who saw the 2005 Dodge Caravan.

As he stood at the driver's door, Styles, 32, was dragged as the driver accelerated and was pinned by the van.

Police said the driver, a 15-year-old boy who doesn't possess a driver's licence, remains in hospital with serious injuries. Charges haven't been laid.

Three other teens were in the van at the time of the incident.

Meanwhile, there is a growing memorial outside the York Regional Police station in Newmarket where Styles was based.

Friends of the officer and strangers have dropped off bouquets of flowers, stuffed animals and cards to offer their condolences and show their support for his family and colleagues.

On one of the cards, a 10-year-old boy wrote this message: "To the Styles family, I know the experience that you are going through. My father died when I was younger, but stay strong. I know my dad and your dad would want you to be."

Outside the 1 District station, flags are flying at half-mast.

A public memorial service is being planned.

To leave a message of condolence, click here.

Brian Patterson, president of the Ontario Safety League and a friend of the Styles family, said the entire community of Newmarket is in mourning.

"This is a real tragedy for our community in Newmarket," Patterson told CP24. "This is an officer who grew up in our community."

Styles, who had been on the force for seven years, was a father to two small children – a two-and-a-half-year-old daughter and a nine-week-old son. His wife Melissa is a civilian employee with the York Regional Police information management department and his father is a retired York police officer.

During his career, Styles received three letters of recommendation and had recently passed a promotional exam to become a sergeant.

With a report from CP24's Cam Woolley