A British citizen was among 14 people killed in a militant attack on a hotel complex in the Kenyan capital Nairobi, sources close to the British government confirmed. An American citizen was also killed, the US state department said,

The bodies were identified based on ID documents found on them when they arrived at Chiromo mortuary, an attendant at the facility told the Reuters press agency. Eleven were Kenyan and two did not have identification papers, he said.

A spokesperson for the Foreign Office confirmed there had been a British citizen killed. They said: “The situation is ongoing. We are in contact with the Kenyan authorities who are coordinating a response and stand ready to assist as required.”

Gunmen blasted their way into the DusitD2 hotel and office complex on Tuesday afternoon. The al-Shabaab Islamist group claimed its fighters were responsible for explosions and gunfire.

Kenya’s interior minister Fred Matiang’i said at 11pm local time that all buildings at the 14 Riverside Drive complex had been secured and the buildings evacuated of scores of people.

But the interior minister did not comment on the attackers’ whereabouts and said security forces were still “mopping up”.

Nearly 11 hours after the assault began, bursts of gunfire and an explosion were heard in the area, suggesting the situation was not yet under control despite the government assurances.

Earlier in the day, office workers had streamed from the complex, some jumping from windows. Security forces continued to escort small groups to safety into the evening, with some hustled into armoured vehicles amid sporadic gunfire.

Foreign security advisers at the site scrambled to make sure their clients were safe.

Kenyan police chief Joseph Boinnet said the attack began with an explosion targeting cars outside a bank followed by a detonation from a suicide bomber in the hotel lobby.

An injured man is taken from the scene (AFP/Getty)

Surveillance video showed three attackers dressed in black running across the parking lot at 3.30pm, shortly followed by a fourth.

At least two of the men were wearing green scarves in the closeup footage. One appeared to be wearing a green belt with grenades in it.

Enoch Kibet, who works as a cleaner in the complex, said: “We were changing our shifts and that is when I heard a loud blast and people were screaming.”

Nairobi hotel attack – in pictures Show all 23 1 /23 Nairobi hotel attack – in pictures Nairobi hotel attack – in pictures Cars are seen on fire at the scene where explosions and gunshots were heard at the Dusit hotel compound, in Nairobi, Kenya Reuters Nairobi hotel attack – in pictures An injured man is evacuated from the scene of an explosion at a hotel complex in Nairobi's Westlands suburb AFP/Getty Nairobi hotel attack – in pictures A soldier takes cover next to a bullet ridden window EPA Nairobi hotel attack – in pictures People run for cover during gunfire and explosions in Nairobi EPA Nairobi hotel attack – in pictures Kenyan security forces take position following an explosion at a hotel complex in Nairobi's Westlands suburb AFP/Getty Nairobi hotel attack – in pictures Security forces on the scene of an explosion in Nairobi AP Nairobi hotel attack – in pictures Cars burn at the scene of an explosion in Nairobi AP Nairobi hotel attack – in pictures People are led away from the scene of an explosion at a hotel complex in Nairobi AFP/Getty Nairobi hotel attack – in pictures A soldier takes cover as gunfire continues at the scene of a suspected terror attack in Nairobi EPA Nairobi hotel attack – in pictures Armed plain clothes officials secure the damaged entrance of a hotel during ongoing gunfire and explosions in Nairobi EPA Nairobi hotel attack – in pictures Members of security forces take cover at the scene Reuters Nairobi hotel attack – in pictures People are evacuated from the scene of a suspected terror attack in Nairobi Reuters Nairobi hotel attack – in pictures Cars burn after an explosion in Nairobi AP Nairobi hotel attack – in pictures A member of security forces holds a weapon at the scene Reuters Nairobi hotel attack – in pictures Security forces advance at the scene of a suspected terror attack in Nairobi Reuters Nairobi hotel attack – in pictures Cars burn at the scene of an explosion in Nairobi Reuters Nairobi hotel attack – in pictures A glass damaged by bullets at the scene Reuters Nairobi hotel attack – in pictures Security personnel on the scene of a suspected terror attack in Nairobi Reuters Nairobi hotel attack – in pictures A woman is helped at the scene of an explosion in Nairobi Reuters Nairobi hotel attack – in pictures Security forces advance at the scene of a suspected terror attack in Nairobi Reuters Nairobi hotel attack – in pictures Security personnel on the scene of a suspected terror attack in Nairobi Reuters Nairobi hotel attack – in pictures Undercover police are on the scene of a blast in Nairobi AP Nairobi hotel attack – in pictures Security personnel on the scene of a suspected terror attack in Nairobi AP

She said she escaped by crawling out of a gate in the basement. “I couldn’t believe I was alive. The blast was so loud and shook the whole complex,” she added.

“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,” a woman working in a bank in the complex said, adding she heard two explosions.

Several large international businesses including Dow Chemical and Reckitt Benckiser have offices at 14 Riverside Drive, and it is also home to the DusitD2 hotel, part of Thai group Dusit Thani. The Australian embassy is across the road.

The complex is about a mile away from the Westgate shopping mall, where al-Shabaab carried out a days-long siege in 2013, killing 67 people.