Hamas militants have fired on the home of a Palestinian police chief in Gaza despite a newly announced ceasefire, Palestinian security sources say.
The ceasefire followed days of clashes between Hamas and Fatah
Gunfire was also exchanged at the home of a head of the governing Palestinian party, Fatah. Several people were hurt.
The ceasefire had followed several days of fighting between Hamas and Fatah. More talks are expected on Wednesday.
Tensions rose when Palestinian Authority forces moved in after Hamas launched rocket attacks on Israel.
Fatah and Hamas leaders announced a truce after two people were killed and several more injured during gun battles between militants from both sides.
Speaking at a late-night Gaza City news conference, the leaders agreed to withdraw all armed forces from the streets of northern Gaza.
But within hours, Hamas gunmen refused to stop at a police roadblock in Gaza and then opened fire on the home of Palestinian police chief Rashid Abu Shbak, the Associated Press news agency reports.
They then fired shots at the home of Abdullah Efrangi, the head of Fatah in Gaza, security sources said.
At least five people were injured in exchanges of fire with bodyguards, hospital staff said, with casualties on both sides.
Keen for 'quiet'
Senior Fatah leader and Palestinian cabinet minister Sufian Abu Zaida played down the incident and said the situation was under control. There were no reports of fresh fighting elsewhere.
Further talks between the factions are expected to take place in Gaza City to consolidate the truce, sources told Reuters news agency.
Hamas spokesman Sami Abu Zuhri said all sides were keen to end the violence, despite the latest incident.
"There is a desire among our movement and the leaders of the Palestinian Authority to put an end to this issue and to implement this 'quiet' on the ground, " he told AFP news agency.
Correspondents say the cause of the tension is the Palestinian Authority's efforts to try to shore up a ceasefire that it has agreed with Israel.
More than 100 rocket attacks by Hamas in and around Gaza in recent days have added to the tension, with Israeli forces threatening to move in if they continue. Hamas says it is still committed to a "conditional calm".
The Palestinian Authority is under pressure to rein in the militants at a time of crucial negotiations with Israel over its planned disengagement from Gaza next month.