Two people have been taken to hospital after 18 stowaways were found in the back of a lorry in sweltering conditions.
Police said the stowaways waved to alert passing motorists who flagged down the driver to stop on the A22 in East Grinstead, West Sussex on Saturday morning.
Immigration enforcement officers said the individuals released from the lorry came from Iraq, Syria and Iran.
A man and a woman were taken to hospital suffering from dehydration, but were later discharged. Water and medical treatment were provided to the others.
Six of the people rescued claimed to be children, and have been passed to social services to have their age assessed.
A Home Office spokesman said: “All will be processed in line with immigration rules.”
The 63-year-old man who was driving the lorry was arrested on suspicion of facilitating illegal immigration and is now in police custody.
Officers said it was vital they reacted quickly in getting people out of the lorry as temperatures in the area soared to 25C (77F).
Sergeant William Keating-Jones, of Sussex Police, said: “Our priority was for the welfare of the occupants who were in the back of the lorry. The vehicle was exceptionally hot and it was important we reacted quickly.
“This was a great multi-agency response to a potentially life-threatening situation, with emergency services, immigration officials, volunteers and even local residents all pulling together.
“We were also mindful of causing minimal disruption to motorists, and the road was closed for about 20 minutes while we were at the scene.”