The Hayat Hotel was popular with the city's lawmakers and government officials. Police have been engaged in an overnight siege in order to retake the building.

At least 12 people have died in an overnight siege after terrorist group al-Shabab attacked a hotel in Mogadishu, Somalia, on Friday.

Security forces were working to retake the building, much of which has been destroyed in the process, early on Saturday.

"So far we have confirmed 12 people, mostly civilians, died," Mohammed, an intelligence officer who only gave one name, told Reuters. "The operation is about to be concluded but it is still going on."

What happened at the Hayat Hotel?

The Hayat Hotel is located near Mogadishu's international airport. It is a popular venue with lawmakers and other government officials.

Al-Shabab militants blasted their way into the hotel on Friday evening with two car bombs, sending huge plumes of smoke over the area. The attackers then opened fire on guests and staff.

"We were having tea near the hotel lobby when we heard the first blast followed by gunfire. I immediately rushed toward hotel rooms on the ground floor, and I locked [myself in]," one eyewitness told the Associated Press. "The militants went straight upstairs and started shooting. I was inside the room until the security forces arrived and rescued me.''

The state-run Somali National News Agency said the "unsung heroes of Somali Police Special Unit" rescued dozens of people during the attack, including children.

What is al-Shabab?

Al-Shabab is a terrorist group linked to al-Qaida that has been fighting against the Somali government — and foreign peacekeepers — for more than 10 years. It seeks to impose a strict interpretation of Sharia law and has been known to stone women to death in the areas that it controls.

The jihadist militant group has claimed responsibility for numerous attacks in Somalia and east Africa, including the 80-hour siege of Nairobi's Westgate shopping mall in 2013 in which at least 67 people died.

Al-Shabab spokesperson Abdiaziz Abu-Musab said on Saturday that its forces were still in control of the hotel and that they had "inflicted heavy casualties."

Last month, Somalia's new President Hassan Sheikh Mohamud said that ending Al-Shabaab's insurgency required more than a military approach, but that his government would negotiate with the group only when the time was right.

Earlier this month, new Prime Minister Hamza Abdi Barre announced that high-profile al-Shabab defector Muktar Robow, who previously served as the group's former deputy leader and spokesman, would be the country's new religion minister.