Residents fled the largest Palestinian refugee camp in Lebanon on Sunday as clashes between security forces and radical Islamists intensified for the third day.
The National News Agency (NNA) said that members of the Bilal Badr extremist group opened fire on the Palestinian security force as they preparing to deploy in the camp.
Among the dead were two civilians, two members of the joint Palestinian security force and one member of the extremist group, the medical sources said.
Sidon's government hospital has been struck by a rocket, and Lebanese authorities have closed the main highway connecting the port city to southern Lebanon.
Fatah is led by Palestinian President Mahmoud Abbas.
Clashes erupted in the camp late Friday as Palestinian factions participating in a joint security force begun deploying throughout the area in the southern city of Sidon.
At least four people have been killed and dozens more people wounded in the latest round of fighting, pitching Fatah and other Palestinian groups against hard line Sunni Islamists known as the Badr group.
In recent months, intermittent deadly clashes have been erupted in the camp and mortar bombs have been used in majority.
During most of the second half of 2016, the camp was also the scene of violent clashes between members of the Jund al-Sham militant group and Fatah fighters.