Somalia’s security forces on Sunday ended a nearly five-hour siege by Islamist extremists at a beachside hotel in Somalia’s capital, said police and a government spokesperson.

At least 15 people were killed when the attackers invaded the Elite Hotel, a new establishment popular with Mogadishu’s young people, said Col. Ahmed Aden, a police officer.

Security forces later killed all four attackers and rescued dozens of people who were trapped inside the hotel, Ismail Mukhtar, spokesperson of Somalia’s information ministry told The Associated Press.

The attack started in the afternoon with a powerful car bomb blast which blew off the security gates to the hotel. Then gunmen ran inside and took hostages, mostly young men and women who were dining there, he said.

Ambulance sirens could be heard in the area which had a power outage when the attack started.

Somalia’s homegrown Islamist extremist rebels, al-Shabab, who are allied to al-Qaeda, have claimed responsibility for the attack via its radio arm, Andalus.

The hotel attack shattered a period of calm that had lasted for a few months. Earlier this year Somalia had a spate of bomb attacks.