A gang of masked men assaulted staff at a distribution warehouse in Daventry before locking them in a room as they drove off with a lorry-full of goods.
The group of four, all wearing balaclavas, arrived at the premises in Newnham Drive on Heartlands Business Park at about 7.10am on Saturday, November 30.
They had a white HGV with a blue curtain-sided trailer and a black Audi A4 displaying false registration plates.
The men assaulted staff and forced them to lie on the floor while they loaded goods onto the trailer, according to police.
The members of staff were then shut in a room while the offenders made off in the vehicles in the direction of the A5.
Witnesses or anyone who may have seen the vehicles in the area around times stated or has any information is asked to call Northamptonshire Police on 101, quoting reference number 19000641235.
Information can also be provided anonymously to independent charity Crimestoppers on 0800 555 111.