Children are among nine people believed to have travelled to England illegally in the back of a lorry.
Bedfordshire Police said the group were discovered in the vehicle at Toddington Services on the M1 northbound, north of Luton, in the early hours on Wednesday.
The nine are currently being checked over by medics. It is believed they travelled to the UK from Europe.
A police spokeswoman said detectives were working to establish the ages, nationalities and identities of those involved, but said the group contained "a mixture of adults and children".