Two Palestinian were killed and four wounded during clashes between rival factions in Lebanon's main refugee camp of Ein el-Helweh.
Palestinian security sources said the two dead men belonged to the Fatah movement of Mahmud Abbas, the Palestinian president.
One, Abu Omar, was allegedly killed by a rival from the Jund ash-Sham movement who was himself wounded when an argument escalated into a gun fight, the source said.
A second Fatah member died of his wounds hours later while three Palestinian women were wounded by stray bullets.
The atmosphere in the camp was reportedly tense following the shooting, with schools and shops shuttered amid fears partisans from both sides could pursue the conflict.
Ein el-Helweh, 45km south of Beirut, is the largest of Lebanon's 12 refugee camps and home to 47,000 Palestinians or their descendants who fled or were forced from their homes when Israel was created in 1948.