Vanuatu police are asking locals and foreigners on Efate to take extra care after the killing of an elderly European couple and an attack on an Englishman.
The police say the murdered couple are from the Netherlands and the third victim, who is in his 60s and is recovering in hospital, is a former school teacher from England.
The acting Commissioner of Police, Arthur Caulton, says a group of seven escaped prisoners may be behind the attacks.
He says one of the prisoners handed himself in over the weekend.
Acting Commissioner Caulton says the group appears to be after money and alcohol.
"These incidents are isolated incidents where prisoners are on the run. We are on full alert to recapture the prisoners, but our message to the whole community, including the expatriates, is that they should be careful in how they are go about their business."
Arthur Caulton says the government has given the police one week to catch the prisoners.