A group of men armed with Kalashnikov assault rifles had initially attempted to get into the hotel, exchanging fire with hotel security, before a suicide bomber detonated an explosive device, the source said.
Hotel guests, reported to include the Norwegian Foreign Minister Jonas Gah Store, were taken to the hotel's cellar to shelter from the assault.
According to Lemar TV, the gunmen hurled several hand grenades into the hotel. The site of the attack was subsequently cordoned off by U.S. soldiers, local police and security agents.
Taliban militants later claimed responsibility for the attack on the Hotel Serena, located close to the presidential palace and the main Defense Ministry building, which is frequently used by foreign embassies for meetings, parties and dinners.