Israeli forces earlier launched missiles at a Hamas base following Palestinian rocket fire, and reporters were trapped by gunfire in Gaza City.
Scores of journalists, mostly Palestinian, remain exposed to fire between Fatah and Hamas gunmen in the center of Gaza City, a Palestinian reporter told Arabic news service Al-Jazeera.
Hours after Fatah and Hamas arranged their latest truce at midnight local time (9 p.m. GMT) on Tuesday, the first reports came of a skirmish near the house of Rashid Abu Shbak, head of the Fatah security service, with both sides blaming the other.
Later, Hamas supporters fired improvised Qassam rockets, injuring several people in the southern Israeli city of Sderot, one rocket nearly hitting the Israeli Defense Minister Amir Perez's house. The Israeli Defense Force reported that at least three more Qassam rockets hit Sderot, in addition to at least two dozen rockets fired on Tuesday. Izzedine al-Qassam Brigades, a militant group linked to Hamas, claimed responsibility for the rocket lauches.
A retaliation air strike in the town of Rafah in the south of Gaza killed at least 3 Palestinians and wounded dozens.
The head of the Palestinian National Authority, Mahmoud Abbas, called chief officials of the Palestinian Liberation Organization to discuss the latest events. According to Palestinian reports, he also arranged to hold a phone conversation with Syrian-based Hamas chief Khaled Mashaal.
Italian Foreign Minister Massimo D'Alema and EU foreign policy chief Javier Solana have called for a ceasefire and international pressure on the warring factions Palestinians to end bloodshed.
Russia's Foreign Ministry issued a statement calling upon the PNA to calm down tensions and ensure a ceasefire.
The pro-presidential Fatah and the more belligerent Hamas, two religious Islamic groups dominating politics in the Palestinian territories, have been fighting a relentless turf war since Hamas gained control of the government in a democratic election last year.
Hamas has refused to recognize Israel and has repeatedly criticized PNA President Mahmoud Abbas for his policies.
The recent outbreak of violence is the first since March, when a national unity government was formed with Saudi mediation. In the past three days, numerous attempts to broker a truce have been quickly upset by skirmishes.
