Immigration officers arrested two men in a dawn raid on a Liversedge business.
UK Border Agency officials and officers from Spen police swooped on Beauty Sleep in Halifax Road early on Wednesday.
Two Pakistani men aged 29 and 30 were arrested on suspicion of being illegal overstayers – remaining in the country after their visas had run out.
A Home Office spokesman said no further action was taken against one man, but the other had overstayed his visa and investigations into his case were ongoing.
On Facebook readers described seeing vans lined up outside the premises and UK Border Agency officers on the Spen Valley Greenway.
Kay Butterworth said: “I saw all the vans and people lined up outside Beauty Sleep being spoken to and put into the immigration vans.”
Michelle Bruce added: “They didn’t have anyone round the back of the building when they raided it, most of them jumped over the wall.”
But Insp Tim Holand from Spen NPT said: “It is thought that out of the 30 or so people in the building at the time one person managed to get away before they could be spoken to.”
Anita Bailey, Home Office enforcement spokeswoman, said: “Where we find people living and working illegally in the UK we will seek to remove them.
“We would urge anyone with information about suspected immigration offenders to get in touch so we can take action.”
Anyone with detailed information about suspected immigration offenders should contact 0113 3865913.
Beauty Sleep did not provide a comment.