Police launched a search in Brighton after students reported witnessing what they feared was a kidnap.
They told police how they saw the teenage victim "cowering" as he was led from a car into woods in the town's Wild Park, off Lewes Road.
Police said the incident could be a misunderstanding and they appealed to those involved to come forward.
The Sussex University students, driving by at the time, reported the sighting to security guards as they arrived at the Falmer campus.
Police were alerted and raced to the scene.
Officers, tracker dogs and the force helicopter, combed the park and surrounding area.
The search was continuing today and police said they were treating the incident seriously.
The victim was spotted with what appeared to be a gag over his mouth in a beige or mushroom-coloured Fiesta, Escort or Metro, possibly with a B-prefix in the registration.
Inspector Kevin Claxton said: "The university students saw the vehicle parked by the side of the Lewes Road, close to the Moulsecoomb police box, just before 7.30pm.
"The boy is about 14 or 15 and was wearing a long-sleeved, light-coloured T-shirt. He was in the front seat."
Det Insp Bill Warner, heading the inquiry, said it was possible the incident was a father-and-son argument. He appealed to those involved to come forward.
Meanwhile, police are carrying out a second search operation, this time for a 13-year-old boy, Jason Hamner-Bennett, who disappeared after leaving his foster home in Moulsecoomb some time after 6pm yesterday.
Jason, who often plays basketball at Hove lagoon, is 5ft 3in with dark hair.
Anyone with information should call police on 0845 6070999.
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