Police said the gang in a vehicle kidnapped the four on March 19 when they were en route to buy some land at Santhayur town. They first released a man who fell sick and told him to get them the ransom and later set free a Kerala government employee.
Police said the government employee in his complaint stated that he recognised two of the kidnappers who had helped him in several deals.
Police said a search is on to trace the gang who have in their custody the other two persons.