British police rescued 18 people from the back of a refrigerated lorry on Tuesday morning, Cambridgeshire police said.
Police received a call at about 11:30 a.m. from the driver of the HGV, who had noticed there were people on board.
Officers found the lorry at the Haddon services on the A1M near Peterborough and rescued 18 people from the back of the vehicle.
The migrants called police from inside the lorry, saying that they were suffocating and struggling to breathe.
The three men, who were “safe and not injured,” were transferred to immigration services.
The cases highlight that “slavery and trafficking are real and police need the public’s help,” Cambridgeshire police said on Tuesday.
Police called on the public to look out for warning signs and call 999 when they spot abnormalities.
Warning signs include hearing banging from the inside of a lorry, and seeing people stealthily emerging from or going inside the back of a lorry.
The police say members of the public should immediately call 999 and take a note of the vehicle registration number if they notice any of these signs.
Human smugglers often hide illegal immigrants inside UK-bound lorries to evade customs checks, a practice that puts the migrants’ lives in danger.