SIDON, Lebanon: A member of Islamist Fatah al-Islam opened fire overnight at the Palestinian refugee camp of Ain al-Hilweh in south Lebanon, wounding one man, following a grenade assault there, Palestinian sources said Monday.

The sources told The Daily Star three hand grenades were tossed at the camp’s vegetable market around midnight.

The market – known as the economic lifeblood of Ain al-Hilweh – is home to members of the mainstream Fatah movement as well as Islamists from Fatah al-Islam and Jund al-Sham.

The sources said one of the grenades exploded outside the house of Fatah al-Islam member Mahmoud Mansour, who, angered by the attack, began firing his gun in the air.

Saleh Owayyed, a Palestinian, was wounded by a stray bullet as a result.

The camp’s security committee has opened an investigation into the attacks.

Security sources said the growing phenomenon of masked gunmen venturing out on the streets of Ain al-Hilweh after midnight has raised fears among the camp’s residents.