Gunshots rang out sporadically as night fell in Nairobi, where police combed the hotel and outlying office buildings for survivors while trying to flush out the attackers.
The attack at the DusitD2 compound, which includes a 101-room hotel, restaurant and office buildings housing local and international companies, began at 3 pm (1200 GMT) with a massive explosion heard five kilometres (three miles) away at the AFP bureau.
The Al-Qaeda linked Somalian group Al-Shabaab, which carried out a notorious assault on a Nairobi shopping mall in 2013, claimed responsibility, according to the SITE Intelligence Group which monitors jihadist activities.
“We can now confirm that this criminal activity commenced at about three o’clock in a coordinated fashion and began at I&M Bank with an explosion that targeted three vehicles in the parking lot, and a suicide explosion in the foyer of Dusit hotel,” said Kenyan police chief Joseph Boinnet.
He said“a number of guests suffered serious injuries” but did not give a figure for any fatalities.
An AFP photographer saw the bodies of five dead, slumped over tables on a restaurant terrace in the complex, while a police source who asked not to be named said he had seen as many as 14 dead.
Elite police forces evacuated terrified workers barricaded in offices after an hour of sustained gunfire as they engaged the attackers.
More than six hours after the attack it was unclear how many people were still hiding inside office buildings or the hotel, owned by Thai giant Dusit Thani Group.