The clashes injured dozens of
There were conflicting reports of casualties, with some news organisations putting the toll as high as eight.
The dead included six members of Yasser Arafat's Fatah movement, reported Reuters.
At least 25 others were wounded when the secular faction clashed Monday with an Islamist group, Osbat Al-Nour, in the south Lebanon Palestinian refugee camp according to medical sources.
Observers said the clashes were part of an ongoing series of battles for control of the Palestinian refugee camp. Tension has been running high between Osbat Al-Nour and Fatah in recent months, often breaking out into street warfare.
Reuters reported that a member of Osbat al-Nour and a civilian were also killed in the shooting, which subsided later in the day following calls by leaders.
A photographer for the Agence France-Presse (AFP) news agency was shot in the foot.
Witnesses said both sides fired automatic weapons and rocket-propelled grenades ahead of the funerals of two people killed in clashes on Saturday.
Over the weekend Osbat Al-Nour's leader Abdullah Shraidi was shot at along with three of his bodyguards as they passed the Fatah office.
Shraidi was seriously injured. Fatah leader in Lebanon Sultan Abu Al-Aynain admitted his group was responsible for shooting the Osbat Al-Nour chief.
Witnesses said armed Islamists patrolled the streets of the camp after the clashes. Representatives of the biggest Islamist factions, Islamic Jihad and Hamas, said they were trying to defuse the situation.
Some mosques called for an end to the fighting, saying only Israel would benefit from the clashes.
Lebanon’s army and security services do not enter the camp where fugitives have often sought refuge. Ain Al-Helwah houses at least 65,000 refugees and is Lebanon's largest Palestinian camp.