Masked gunmen killed a Palestinian commander in the Ain al-Helweh refugee camp in southern Lebanon on Monday, a camp official told AFP.
"Two masked gunmen on a motorcycle... opened fire with a machine gun on Mohammed Zeidan in front of his home," the camp official from the mainstream Fatah faction of Palestinian president Mahmud Abbas said.
"He was transferred to a health centre but was pronounced dead on arrival," the official added, speaking to AFP on condition of anonymity.
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A camp medic said Zeidan had been sprayed with at least 15 bullets.
Armed Fatah loyalists took to the streets of Ain al-Helweh as the news broke.
The killing is the latest in a spate of attacks targeting officials in Lebanon's largest Palestinian refugee camp outside the southern port of Sidon.
Some 350,000 Palestinians live in Lebanon, most of them in a dozen camps dotted around the country.
Lebanese forces leave security inside the camps largely in the hands of the Palestinian factions.