Eighteen people have been rescued from the back of a refrigerated lorry at a motorway service area.
The driver noticed people on board when he stopped at the Haddon services on the A1(M) near Peterborough, at about 11:30 GMT, police said.
Officers said paramedics were sent after the driver alerted police, and none of the 18 people were injured.
There were no arrests and those on board have been handed to the immigration services.
Cambridgeshire Police said the driver who telephoned them “had noticed the people on board and was concerned for their welfare”.
In October 2019, 39 Vietnamese migrants overheated and suffocated in a sealed refrigerated lorry that was not turned on.
Last week three men were rescued from the back of a refrigerated lorry in Brampton, Cambridgeshire, after telephoning police to say they were “suffocating” inside.
Officers asked people to look out for the “warning signs” of potential trafficking including hearing banging from the inside of a lorry, things being thrown from lorries in order to grab the attention of other motorists, or groups of people trying to get in to lorries, or emerging from them.