The arrested persons were identified as Eegala Chinayya, Eegala Ramakrishna and Eegala Maridayya, all brothers.
Inspector Sheikh Gafoor of Narisipatnam rural police station said the trio killed their relatives S Ramu (35) and Eegala Pothamma (40) and injured E Varalakshmi on the evening of May 18.
Sharp weapons and iron rods were used in the attack, which was a fall-out of a land dispute between two families, he said. A case related to the dispute was also pending in the High Court.