Four people have been arrested in connection with a "brutal" attack on a family by robbers who demanded the keys to their businesses.
John and Melanie Fox and their adult daughter were attacked in Hawksdown Road, Walmer, near Deal, on 29 June.
A man, 23, two men aged 20 and a woman aged 21, all from Dover, were arrested on suspicion of robbery on Friday.
Kent Police said the suspects were being questioned at Dover and Folkestone police stations.
The gang, which tied up the family and beat them with baseball bats, also carried guns when they broke into the house.
The robbers wanted they keys to Crabble Post Office and the Londis store in Cherry Tree Avenue, both in Dover, which the family run.