Palestinian security officials said they arrested about 50 people following the incident.
Soldiers have since carried out house-to-house searches in villages in the Hebron area near the Kiryat Arba settlement where the two couples, including a pregnant woman, were killed yesterday evening.
'It appears that the attack was carried out by a passing vehicle, however the investigation is still under way,' the Israeli military said.
Military Chief of Staff Lieutenant General Gabi Ashkenazi and other generals conducted 'operational and intelligence situation assessments' at the scene, the military said.
'We are operating on a number of different levels since the event took place and will continue to act until we get a hold of the terrorists,' Lt Gen Ashkenazi said.
'The IDF (Israel Defence Forces,) together with the rest of the different security apparatuses, is operating and will continue to do so until we catch the murderers responsible for this event,' he said.
Security forces set up roadblocks in the area.
Palestinian forces arrested about 50 people during the night, a security official said.
He said the suspects were supporters of Hamas.
The attack was claimed by the Ezzedine al-Qassam Brigade, the armed wing of Hamas, which is vehemently opposed to the talks that Prime Minister Benjamin Netanyahu and Palestinian president Mahmoud Abbas are to relaunch in Washington on Thursday.
Killings condemned
Israeli Prime Minister Benjamin Netanyahu said the spilling of the 'blood of Israeli civilians' would not go unpunished as he promised to hunt the killers.
Elsewhere, European Union foreign policy chief Catherine Ashton condemned the killings saying 'enemies of peace' were trying to derail fresh Middle East peace talks.
'I strongly condemn the terrorist attack that has killed four Israeli civilians near the city of Hebron,' Ms Ashton, who is currently in China for high-level strategic talks, said in a statement.
