Police are hunting for six people in the Moulton Seas End area seen running from a lorry container towards Holbeach.
Eight people in total were see seen leaving the vehicle on the A17 in Fosdyke.
Two have been court and detained on suspicion of entering the UK illegally, but six more remain on the run.
A statement from Lincolnshire Police, said: “At 1.19pm today (January 8) we received a report that eight people were seen running from a lorry container on the A17 Main Road in Fosdyke.
“Two have been detained on suspicion of entering the UK illegally under the Immigration Act. Our search for the other six continues.
“The individuals were seen heading down the A17 towards the Holbeach area. They could be in the Moulton Seas End area or neighbouring villages or fields.
“A search is underway by local officers, officers from Emopss including a dog handler to locate these individuals and a National Police Air Service helicopter is assisting us in our search.
“These individuals are reportedly wearing dark clothing. They may be in need of medical treatment.”
Andy Morrice, Boston inspector, said: “We are asking residents to check their out-buildings and gardens. If anyone sees anyone acting suspiciously they should call us.”
If anyone suspects they have seen one of these people, please contact Lincolnshire Police on 101 quoting incident number 192 of January 8. In an emergency call 999.