The clashes between members of the ruling Palestinian movement Fatah and the Bilal Badr Islamist movement erupted five days ago.
“Since last Thursday, two people were killed, eight were injured,” the source said, noting that the killed Palestinians were members of the Bilal Badr movement.
Militants allegedly linked to the Islamic State (Daesh) and Jabhat Fatal al Sham terror groups, both outlawed in Russia, may have taken part in the clashes.
On Monday, militants used mortars along with assault rifles and grenade launchers. The Lebanese army increased the alert level, blocked all the roads for vehicles in the area and opened a humanitarian corridor for all civilians willing to leave their homes.
Ain el-Hilweh, the largest Palestinian refugee camp in Lebanon, was founded in 1948 near the city of Sidon.