Terrie Kirby died along with her three friends, Ryan Beal and Brandon Brown, both 20, and Alexandra Binns, 18, when their quad bike was hit by a sports car on the A6201 between Upton and Hemsworth on Sunday.
Flowers and 16th birthday balloons have been left at the side of the road near where the quad bike they were riding on was hit by a Nissan 350Z at around 12.30am.
Three of the group died at the scene while one of the men died in hospital from his injuries. All of the victims were from the Upton area.
St Wilfrid’s Catholic High School in Featherstone, where Mr Brown was a pupil, will install a plaque at the school in his memory.
Two men, aged 21 and 22, who were in the Nissan were arrested on suspicion of dangerous driving and have been bailed pending further inquiries.
Det Chf Insp Richard Holmes, of the Homicide and Major Enquiry Team, said: “A number of witnesses have told police that a short time before the collision, the Nissan 350Z was seen parked up nearby, along with a number of other cars. Police urgently need to speak to any occupants of those cars.
“We also now know from witnesses that the quad bike was in and around Hemsworth town centre about an hour before the collision and also ask any witnesses who may have seen it to come forward.
“Officers are continuing their meticulous enquiries at the scene and it is vital that we speak to anyone who may be able to provide information, no matter how small. This is a tragedy for the families of those involved and a huge shock to the whole community.”
Anyone with any information should contact West Yorkshire Police’s homicide and major enquiry team on 101 or Crimestoppers, anonymously, on 0800 555111.