BEIRUT (AP) — A bomb blast in a Palestinian refugee camp in Damascus killed four people and seriously wounded a member of a faction that has backed Syrian President Bashar Assad in the country's bitter civil war, activists said Friday.

Syria's Foreign Ministry, meanwhile, lashed out at neighboring Turkey, which has sheltered anti-Assad fighters.

The ministry denounced Turkey's request for NATO Patriot surface-to-air missiles along its border with Syria as "a new provocative step." Turkey made the request earlier this week to bolster its defenses and prevent a spillover of the Syrian civil war onto its territory.