Police stopped the vehicle at the Findon end of Long Furlong Road just after 1pm after a call at around 12.45pm, a force spokesperson confirmed.
Five units were assigned to the incident.
The group, believed to be all of adult age, have been detained and the incident is under investigation, according to police.
Eyewitness Stuart Minton, who drove past the incident, said he saw a big white lorry surrounded by police cars, with one of the men detained in handcuffs.
The private hire car driver added that the lorry was facing in a southward direction towards Littlehampton.
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