http://www.bbc.co.uk/news/world-middle-east-12721170The five were members of the same family, a couple and three children, according to Israeli media reports.
The overnight attack occurred in the Itamar settlement, near Nablus in the northern West Bank. The Israeli army is now searching the area for the suspect.
The incident comes as peace efforts between Israel and the Palestinians have ground to a halt.
The family - including a baby and children aged 11 and three - were stabbed to death, Israeli media reported.
The Itamar settlement was the target of a previous attack, in 2002, in which five Israelis were killed and several injured in an attack by a Palestinian gunman.
US-brokered peace talks between Israel and the Palestinians stalled late last year over the issue of Israeli settlement building.
Palestinians have refused all direct contact with Israel until construction is frozen.
Nearly half a million Jews live in more than 100 settlements built since Israel's 1967 occupation of the West Bank and East Jerusalem.
They are held to be illegal under international law, although Israel disputes this.
Topic: "Palestinian" 'kills five Israelis' in West Bank attack (Read 374 times)