Fifteen people have been found in the back of a lorry in Wiltshire following reports of "suspicious activity" involving the vehicle.
Wiltshire Police said they closed the A350 at the Kington Langley crossroads near Chippenham after being called by a member of the public shortly before 8.30pm on Wednesday.
A man in his 50s has been arrested on suspicion of assisting with illegal entry and is in custody in Swindon.
All of the people who were discovered in the lorry are believed to be over the age of 16 and none is thought to be in a serious condition, according to police.
One person has been taken to hospital for further checks while the others have been taken into custody.
A police spokesman said: "We were called by a member of the public shortly before 8.30pm this evening following a report of suspicious activity involving a lorry on the A350 near Chippenham.
"Officers attended the scene and located 15 people in the rear of the vehicle.
"At this early stage of our investigation, we believe they are all over the age of 16."
The road closure is expected to stay in place while the lorry is recovered.
We were called by a member of the public shortly before 8.30pm this evening following a report of suspicious activity involving a lorry on the A350 near Chippenham.
Officers attended the scene and located 15 people in the rear of the vehicle.
— Wiltshire Police (@wiltshirepolice) November 6, 2019
It comes after eight people were arrested earlier this week by Vietnamese police in connection with the 39 migrants found dead in a lorry in Essex.
They were held on Sunday on suspicion of organising people smuggling overseas.
The 31 men and eight women who were discovered in the back of the refrigerated truck in Grays in October are thought to have been Vietnamese.
So far two people have been charged.
Essex Police have started extradition proceedings to bring 22-year-old Eamonn Harrison from Ireland to the UK.
Harrison, of Newry in Co Down, Northern Ireland, appeared at Dublin High Court last Friday charged with 39 counts of manslaughter, along with human trafficking and immigration offences, and was remanded in custody.
The driver of the lorry, Mo Robinson, 25, appeared at Chelmsford Magistrates' Court charged with 39 counts of manslaughter, conspiracy to traffic people, conspiracy to assist unlawful immigration and money laundering.
Detectives have also urged Ronan Hughes, 40, and his brother Christopher, 34,said to have links with the road haulage and shipping industries, to hand themselves in.
The pair, from Armagh in Northern Ireland, are wanted on suspicion of manslaughter and human trafficking.