Rival groups have clashed in the Gaza Strip, two days after the Islamic militant group Hamas swept to victory in Palestinian polls.
Fatah gunmen said their leadership was corrupt and inefficient
The worst trouble flared up in Khan Younis. Several were wounded when Hamas activists exchanged fire with members of Fatah - which lost the election.
Fatah activists also rallied against their own leaders, blaming them for the defeat and setting cars on fire.
Palestinian leader Mahmoud Abbas has said Hamas should form a new cabinet.
Hamas won 76 of the 132 seats in Wednesday's parliamentary elections and has the backing of a further four independent MPs.
However, it is facing increasing international pressure to renounce violence against Israel and possibility that foreign donors may withhold millions of dollars in aid to the Palestinians.
At least eight people were injured in several gun battles in and around Khan Younis - in what were the first armed clashes between Hamas and Fatah groups since the elections.
At least four police officers were also wounded during the shootings.
Also on Friday, thousands of Fatah members outside the legislature in Gaza and in the refugee camp of Nusayrat called for the entire Fatah leadership to go, accusing them of corruption.
They set fire to government cars and firing shots into the air.
One protester toured the area in a van, telling fellow demonstrators through a loudspeaker: "Fatah lost because of the central committee so we call for them to resign."
The rallies against Mr Abbas included those from militant Fatah offshoots like the al-Aqsa Martyrs Brigade.
One militant told AFP news agency: "We want him (Mr Abbas) and his entire team out."
The violence came as senior Hamas leader Ismail Haniya said Mr Abbas had agreed to meet shortly to start consultations on "a political partnership" and the make-up of the next administration.
Mr Haniya on Friday made his first big speech since the election victory near Gaza City's waterfront.
He told a packed mosque: "When we are calling for unity and partnership it is not because we are afraid or weak or incapable of facing the challenges ahead, but because we believe in unity."
The BBC's Alan Johnston at the mosque in Gaza says an alliance may be necessary for, if Hamas were to try to govern alone, interaction with the outside world might be extremely difficult.
As it is, he says, some Palestinians are concerned that crucial international financial support may be cut back.
US President George W Bush said late on Friday that Washington would cut its aid to the Palestinians unless Hamas renounces violence and stops calling for the destruction of Israel.
"We won't be providing help to a government that wants to destroy our ally and friend," Mr Bush said in an interview with CBS.
Earlier, the European Commission, which offered 280 million euros ($342m) to the Palestinian people last year, admitted it was in a dilemma about funding.
On Friday President George Bush said US aid to the Palestinians would halt unless Hamas dissolved its armed wing and stopped threatening Israel.
Israel has ruled out any talks with Hamas, which it calls "an armed terror organisation that calls for Israel's destruction".
The US, UN, EU and Russia on Thursday urged Hamas to renounce violence and accept Israel's right to exist.
The four powers working for peace in the Middle East will hold talks in London on Monday.