The British national killed in an attack in Nairobi has been named as Luke Potter.
Gunmen stormed the DusitD2 complex in the Westlands district of the Kenyan capital on Tuesday afternoon, setting off explosions and killing 14 people.
Special forces were sent into the hotel to flush out the gunmen and the Interior Ministry said the area had been secured on Tuesday night.
Potter, international development charity Gatsby’s Africa programmes director, had worked for the organisation for 10 years.
A statement said: “We are deeply shocked and saddened to confirm that Luke Potter, our Africa Programmes Director, was killed in the recent security incident in Nairobi.
“Luke had devoted the past ten years of his career to helping some of the poorest and most vulnerable people in the world. He had worked with us for three and a half years, carrying out assignments across East Africa.
“Luke was instrumental in establishing our forestry programme and team in Kenya, and provided crucial leadership, guidance and support to our Tanzanian forestry programme and our tea programmes in Rwanda and Tanzania.”
The statement continued: “Luke was respected by all he worked with, bringing huge drive, determination, a relentless work ethic, and a thirst for new ideas to every project.
“He brought a calm head and his unique sense of humour to every situation. He was deeply committed to his work, to his teams, to Gatsby and to development in Africa. He was our colleague and our friend.
“We share the grief of his family, partner, daughter and friends.”
Announcing the end of the operation to secure the area on Wednesday, Kenyan president Uhuru Kenyatta said: “All the terrorists have been eliminated.”
It is understood a member of the SAS was involved in the mission, although the MoD said it does not comment on special forces. Another Briton was wounded in the attack.
Images showed a heavily-armed man with a military vest and balaclava working with local forces and helping victims leave the complex.
It was reported the lone SAS member was involved in the operation, along with US Navy seals, having been in the country to train Kenyan special forces.
In a video posted on Twitter, the UK High Commissioner to Kenya, Nic Hailey, confirmed that at least one British national was killed in the attack.
“Our team at the High Commission was working through the night to support the Kenyan authorities as they responded to this attack and offer all the help we can to all the British nationals who may have been caught up in it,” he said.
“I am very sad to confirm that at least one British national has been killed in the attack.
“We are providing our support to his family and friends at this very difficult time and our thoughts are with them.”
A Foreign Office spokesman said: “We are supporting the family of a British man killed in the recent terrorist attack in Kenya.
“We are also supporting a British person who was wounded during the attack and is receiving medical attention.
“We stand ready to help any other British people affected.”
The San Francisco-based company, I-DEV International, confirmed that American Jason Spindler, the firm’s co-founder and managing director, was killed, while nine others were safely evacuated from its Nairobi office.
London-based firm Adam Smith International said two of its employees were shot dead in a cafe during the attack.
A statement released by the company said Abdalla Dahir, 33, and Feisal Ahmed, 31, who were both Somali-Kenyans, were killed on the terrace of a restaurant in the complex where the firm has an office.
Another 50 staff and consultants were safely evacuated, the statement added.
Special forces were sent into the hotel to flush out the gunmen believed to be holed up inside and the interior ministry said the area had been secured on Tuesday night.
However gunfire and another explosion were later reportedly heard at the scene.
On Wednesday morning the National Police Service said the area remained “under an active security operation” and ordered people to stay away “until it is declared safe”.
In a televised address later, Kenyatta said more than 700 people were evacuated during the security operation and urged Kenyans to “go back to work without fear”, saying the country was safe for citizens and visitors.
The president said he did not know how many attackers were involved.
Al-Shabab - the Somalia-based group that carried out the 2013 Westgate Mall attack in Nairobi in which 67 people died - has claimed responsibility for the atrocity.
Foreign Secretary Jeremy Hunt said on Twitter: “Really tragic news from Kenya - my thoughts are with the families and friends who have lost loved ones in this attack including one British citizen.
“UK stands with Kenya at this difficult time. Our team in Nairobi are supporting all Brits affected.”
The Kenya Red Cross said it was helping families searching for loved ones missing since the attack began.
The British Army Training Unit in Kenya (BATUK) has a permanent base in Nanyuki, around 120 miles from Nairobi, with a smaller element in the country’s capital.
The unit consists of around 100 permanent staff and a short tour cohort of 280 personnel, according to the MoD.
Under an agreement with the Kenyan government, up to six infantry battalions per year carry out eight-week exercises in the country, along with Royal Engineer exercises and medical deployments.