Gunmen took at least 170 people hostage at a Radisson Blu hotel in the former French colony of Mali Friday, U.S. Embassy officials and a hotel spokesman told NBC News.
The raid on the upscale hotel, near government ministries and diplomatic offices in the capital Bamako, comes a week after attackers killed 129 people in Paris.
"They have locked in about 140 guests and about 30 employees," said a spokeswoman for the Carlson Rezidor group, which owns Radisson, told NBC News. "So the hotel is locked down and there is no possibility to go out or come in."
A security source told Reuters that 10 gunmen attacked the hotel, but that report could not immediately be confirmed by NBC News.
Witnesses in the area said police had surrounded the hotel and were blocking roads leading into the neighborhood, it reported.
"As per our information the persons who have entered the building and have initiated the hostage-taking have locked the property, so it is not locked by police or other forces," the hotel spokeswoman added.
The company said it was working to establish the names and nationalities of those taken.
The U.S. Embassy in Mali said it was aware of an "ongoing active-shooter operation at the Radisson Hotel."
"The U.S. Embassy staff has been asked to shelter in place," it said. "All U.S. citizens should shelter in place. Private U.S. citizens are encouraged to contact their family. Monitor local media for updates. U.S. citizens should adhere to the instructions of local authorities and monitor local media."
In August, the Embassy issued a security message informing U.S. citizens "of a heightened security risk to westerners in southern Mali, including the area outside Bamako city."
Meanwhile, a Chinese guest with the family name Chen told China's state-run Xinhua news agency that he was among a number of Chinese guests trapped in the hotel.
Northern Mali was occupied by Islamist fighters, some with links to al Qaeda, for most of 2012 until they were driven out by a French-led military operation.
An Islamist group claimed responsibility for the death of five people last March in an attack on a restaurant in Bamako that is popular with foreigners.