Avon and Somerset Police say they have stopped a lorry containing 20 people suffering from possible dehydration.
The vehicle was stopped at a service station off the A303 at Southfields roundabout near Ilminster, Somerset at about 1pm.
"Their health and welfare is paramount as we try to piece together with the immigration authorities exactly what has happened," a police statement said.
More top news
The Chancellor has hailed Lloyds Banking Group's quadrupled profits as a "milestone". So do the bosses deserve millions for a job well done?
Ed Miliband has just announced Labour's 'plans for young people', while David Cameron has pledged to protect pensioners.
Responding for the first time to recent questions over the death of a steward, Walsh insisted the evidence said cabin air was safe.