Gunmen attacked a five-star hotel in Mali's capital Bamako on Friday and are holding 170 hostages, witnesses said.

Attackers shouting "Allahu Akbar" opened fire outside the Radisson Blu Hotel in the centre of the capital before storming it. Al Jazeera reports that the richest man in Africa, Aliko Dangote is a guest in the hotel.

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Automatic weapon fire could be heard from outside the 190-room hotel where security forces set up a security cordon.

Speaking to Al Jazeera by phone from Bamako, business owner Garba Konate said a group of attackers showed up about three hours earlier.

"About 10 gunmen arrived early in the morning and shot all the guards in front of the Radisson," Konate said.

One of the guests reportedly staying at the hotel is Nigerian Aliko Dangote - the richest person in Africa.

"I started hearing gunshots coming from the hotel," said Ibrahim, 28, who works at a cultural centre 40 metres away from the hotel.

"Soon after I saw one of the guards running out, injured... The security guard told me the shooters were so quick that he doesn't even know how many came in," he told Al Jazeera.

The hotel's owner said it "is aware of the hostage-taking that is ongoing at the property today... As per our information two persons have locked in 140 guests and 30 employees," the company said in a statement.

The shooting follows a 24-hour siege and hostage-taking situation at another hotel in August in the central Malian town of Sevare.

Four soldiers, five UN workers, and four attackers were killed in that attack.

Armed groups have continued to wage attacks in Mali despite a June peace deal between former Tuareg rebels in the north of the country and rival pro-government armed groups.

Northern Mali fell in March-April 2012 to al-Qaeda-linked groups long concentrated in the area before being removed by a France-led military operation launched in January 2013.

Despite the peace deal, large swathes of Mali remain beyond the control of government and foreign forces.