Supporters of the ruling Hamas movement and Fatah have exchanged fire in Gaza, ignoring a ceasefire announced on Saturday.
Mortar bombs exploded near the offices of Mahmoud Abbas, the Fatah leader and Palestinian president, on Sunday as two members of his presidential guard died from gunshot wounds sustained in fighting over the weekend.
The latest deaths raised to 27 the number of Palestinians killed in factional clashes in the past four days. Hamas denied firing the mortar bombs at Abbas' office which caused no injuries.
The violence has brought life to a near-standstill for residents of the narrow coastal strip.
Some Gaza residents ventured on to the streets for the first time in days to find masked fighters manning checkpoints and most stores closed despite the latest ceasefire deal.
More than 80 Palestinians have been killed in the fighting since December, when unity government talks between Hamas and Fatah broke down and Abbas called for new elections.
Accusations
Fawzi Barhoum, a Hamas spokesman, said its fighters were abiding by the truce. He accused Fatah of failing to withdraw its forces from the streets.
Tawfiq Abu Khoussa, a Fatah spokesman, accused Hamas of planting bombs on key roads and shooting from rooftops into a main security compound.
Fatah and Hamas officials said further talks would be held on Sunday on implementing the terms of the truce.
In a related development, Shimon Peres, the Israeli deputy prime minister, has said Israel does not intend to intervene in the Gaza Strip, adding that any attempt of this kind would put Israel in a difficult situation.