Residents of Haiti's capital scrambled for safety Saturday following the latest spasm of gang violence, with a U.N. group warning of a "city under siege" after armed attackers targeted the presidential palace and police headquarters.

Criminal groups, which already control much of Port-au-Prince as well as roads leading to the rest of the country, have unleashed havoc in recent days as they try to oust Prime Minister Ariel Henry as leader of the Western hemisphere's poorest country.

On Saturday, dozens of residents were seeking safety in public buildings, with some successfully breaking into one facility, according to an AFP correspondent.