Suspected militants have attacked a luxury hotel complex in Nairobi, killing at least 15 people.
The compound in the Westlands district of the Kenyan capital, which houses the DusitD2 hotel as well as offices, was attacked by gunmen on Tuesday.
By the evening officials said the siege was over but gunfire and explosions were heard early on Wednesday and a security operation is ongoing.
The Somalia-based militant group al-Shabab said it was behind the attack.
Police sources say 15 people have been killed, but an official number has not yet been confirmed by the government.
Some civilians are reportedly still trapped in the complex, and some have been texting relatives from hiding places.
A US citizen is among the dead, according to the US State Department.
The fate of the attackers is also unclear.
How did the attack unfold?
The attack began at about 15:00 local time (12:00 GMT) when four gunmen threw bombs at vehicles in the car park before entering the lobby, where one blew himself up, police say.
A woman working in a neighbouring building told Reuters news agency: "I just started hearing gunshots, and then started seeing people running away raising their hands up and some were entering the bank to hide for their lives."
Security camera footage showed at least four heavily armed men walking in and opening fire. There are reports they had been seen visiting the compound in recent days.
At 20:00 GMT, Interior Cabinet Secretary Fred Matiang'i said all the buildings in the complex had been secured by security forces.
"The situation is under control and the country is safe," he told reporters. "Terrorism will never defeat us."
But just an hour later gunfire and sporadic explosions were reported in the area.
Security forces then combed their way through the building with reports saying frightened workers had barricaded themselves inside.
In the early hours of Wednesday, more than 100 people were rescued from the complex and taken to a nearby trauma centre.
About 30 people are being treated at Nairobi hospitals, media reports say, while the security operation is ongoing.
The five-star DusitD2 hotel has 101 rooms. Located in the Westlands suburb, minutes from the capital's business district, it has its own spa and several restaurants.
Kenya has seen a number of terror attacks in recent years - most notably in areas close to the Somali border and in the country's capital.
Striking close to home
By Joe Inwood, BBC News, Nairobi
Every person escaping the Dusit complex has the same story - heavily armed men firing indiscriminately, using bombs and automatic rifles to kill. Most were too shaken to talk. They were all relieved to have escaped.
They were coming out in small groups, many hours after the first explosions. The blasts could be heard across the city. I was in my flat round the corner when they happened, followed by the unmistakable sound of gunfire.
The pictures that have been coming from inside are truly horrific. Ordinary people going about their business, murdered as they had lunch or did their jobs.
This has a personal feel, too. The restaurant that seems to have taken the brunt of the explosions is a place I know well. It was full of lovely staff who would always greet you with a smile. As I sit watching the survivors escape, I wonder how many of them didn't make it.
Who are al-Shabab?
They are a militant Islamist group that opposes the Somali government but has also carried out attacks throughout East Africa.
Kenya is part of a regional peacekeeping operation that supports the Somali government in its battle against al-Shabab.
During an 80-hour siege at the upscale centre, 67 people were killed.
Two years later, the group carried out its deadliest ever assault in Kenya, shooting dead almost 150 people at Garissa University.