Four people have been arrested for immigration offences at a shop, flat and restaurant in Torbay, the UK Border Agency said.
Two Indian men in Torquay, one found in a flat and one in a shop, were working in breach of their student visas.
A Chinese man and woman attempted to flee from officials at a restaurant in Paignton. They were both found to have expired visas.
All four have been taken to Torquay police station, pending deportation.
Businesses employing illegal immigrant staff face penalty fines of up to £10,000 per worker employed, the agency said.