Two British-Israeli sisters were killed and their mother badly injured in a gun attack on their car in the West Bank.
The attack took place near an Israeli settlement in the Jordan Valley and the girls’ father witnessed the incident from a separate car following behind, local officials said.
In London, the Foreign Office confirmed the deaths and appealed for all sides in the Israel-Palestine dispute to de-escalate a situation which has seen violence flare up in recent days.
There was further bloodshed in Tel Aviv, as Britons were reportedly among those injured when a car rammed into a group of people near a popular seaside park.
An Italian man was killed in the attack, but reports suggested Britons were among six people injured.
He said: “With great sorrow we received an update on a shocking terrorist attack in which terrorists shot a car including a mother and her two daughters, residents of Efrat.
“The two girls were murdered and the mother is in (a) critical condition and we all pray for her quick recovery.
“The father of the family who drove in another car from the front turned around and witnessed the efforts to take care of his wife and daughters.”
A Foreign Office spokesman said: “We are saddened to hear about the deaths of two British-Israeli citizens and the serious injuries sustained by a third individual.
Shadow foreign secretary David Lammy said: “I am shocked by reports of the killing of two British sisters in an appalling and cowardly attack in the West Bank.
“My thoughts are with their family and loved ones. More civilian victims of this cycle of violence show the urgent need for diplomatic efforts to de-escalate.”
Foreign Secretary James Cleverly had earlier called for calm after Israel launched strikes in southern Lebanon and bombed targets in the Gaza Strip in retaliation over rocket attacks.
The cross-border fighting, while Jews are celebrating the Passover holiday and Muslims are marking Ramadan, erupted following violent scenes at Jerusalem’s Al-Aqsa Mosque.
The Israeli strikes in southern Lebanon came after militants fired nearly three dozen rockets from there.
The Israeli military said it targeted installations of the Palestinian militant group Hamas in Lebanon.
Mr Cleverly said both sides in the Israel-Palestine dispute should “recommit themselves to a negotiated settlement”.
“Now is the time for all parties across the region to de-escalate tensions.
“At the convergence of Passover, Ramadan and Easter, the UK calls for all parties to respect the historic status quo arrangements at Jerusalem’s holy sites and cease all provocative action.
“The UK is a strong supporter of freedom of religion or belief and calls for places of worship to be respected.
“We value Jordan’s important role as custodian of the holy sites in Jerusalem and condemns the Israeli police violence at the Al-Aqsa Mosque.
“When Israeli security forces conduct operations, they must ensure they are proportionate and in accordance with international law.”
In Jerusalem, violence flared again at the Al-Aqsa Mosque before dawn prayers, with Israeli police stationed at one of the gates forcibly dispersing vast crowds of worshippers who chanted praise for Hamas.
Human rights campaign group Amnesty International UK criticised Mr Cleverly’s response.
The charity’s Kristyan Benedict said: “James Cleverly’s belated response to shocking Israeli violence against Palestinians at Al-Aqsa Mosque isn’t just weak and tokenistic – it’s also dangerously misguided because it effectively isolates individual incidents of violence from the overall context, which is decades of apartheid, occupation and systematic injustice against the Palestinian people.
“Despite the Foreign Secretary’s usual platitudes about ‘peace’ and ‘de-escalation’, the UK continues to oppose vital international measures such as the ongoing ICC (International Criminal Court) investigation, designed to bring justice and accountability for Israeli and Palestinian civilians.”