A small group of just two caravans arrived at Jonesco on Caxton Way, Fulwood, shortly after 11am on Saturday.
The group have been seen in the car park of the manufacturing company.
Jonesco, which was established in 1967, is a family-run manufacturing company which makes mudguards.
The business is closed on Saturdays and does not open again until Monday.
Jonesco have been approached for comment.