The U.S. State Department confirmed that one American was killed in the attack.
By midnight, the assault had morphed into a standoff as armed forces continued to clear the complex. Early Wednesday, Kenya’s Interior Ministry said on Twitter that all buildings had been secured and there was no further threat to the public, the Associated Press reported.
Kenya National Police chief Joseph Boinnet said the attack began with “a suicide explosion in the foyer of DusitD2 hotel, where a number of guests suffered severe injuries.” He said in a late-night news conference that only the top floor of the hotel remained to be cleared.
His counterpart, Interior Minister Fred Matiang’i, added, “We are now in the final stages of mopping out the area and securing evidence and documenting the consequences of these unfortunate events.” But heavy gunfire and large explosions could still be heard occasionally, and the number of civilians remaining inside the complex was unknown.
The Somali militant group al-Shabab told several international media organizations that it was behind the attack. “We are currently conducting an operation in Nairobi,” the group’s spokesman said to Al Jazeera.
The assault started about 3:30 p.m. just outside the Dusit hotel and office park on Riverside Drive in Nairobi’s Westlands neighborhood. Throughout the day, heavily armed security forces moved slowly through the complex evacuating people from its five buildings as frightened civilians poured onto a nearby street with their hands in the air.
The hotel — part of a Thai-owned chain — is popular for conferences and news briefings, and the complex also hosts scores of shops and offices, including those of many multinational companies such as Visa and Shell. It is also a popular shopping destination. Before Tuesday, it would have been considered one of Nairobi’s safest spaces.
Those being evacuated represented Nairobi’s diverse, international workforce. The city is home to tens of thousands of expatriates and is considered the economic hub of East Africa.
Many of the multinational companies with offices in the complex appeared to have their own private security working alongside Kenyan security forces to move their workers to safety.
Four hospitals in the city were taking victims. One of them, Kenyatta National Hospital, said four people were brought in with bullet wounds.
Yvonne Nkirote, who works at the Redhouse communications firm in the hotel complex, said she had stopped by the Amadiva nail salon when she heard a massive explosion.
“I saw body parts and blood on the ground right outside,” she told The Washington Post as police escorted her out of the complex. There, she was reunited with several work colleagues, and they burst into tears on finding one another other safe.
Another worker at the complex, Sandeep Sura, said he saw the attackers. “I saw two very young guys with AK-47s,” he said, adding that they were dressed in full black. Sura said all of the upper floors of the complex’s buildings are accessible only by magnetic key cards or fingerprint scanners.
Efforts to contact those remaining in the complex were unsuccessful, but some used social media to appeal for help.
“I am in 14 Riverside drive hiding in a bathroom and we are under attack,” tweeted one man who described himself as being at the scene of the blast. “There was a massive bombs blast then gunshots, please.”
A U.S. State Department spokesman said in a statement that the U.S. Embassy in Nairobi was monitoring the attack.
“We condemn this senseless act of violence,” the spokesman said. “We are working with the Kenyan authorities to determine if there are any U.S. citizens affected.”
Kenya has been attacked repeatedly by fighters from the Islamist al-Shabab movement, which is based in neighboring Somalia. The worst of the attacks in Nairobi took place in 2013 at the Westgate mall, killing 67 people. Four attackers also died during a three-day standoff.
Kenyan forces are part of an African Union-led coalition that has about 20,000 troops in Somalia, aiding the ill-equipped and poorly trained Somali National Army. Kenya’s air force conducts regular airstrikes against al-Shabab targets.
The bulk of airstrikes are carried out by the U.S. military’s unmanned drones, which conducted 47 strikes in 2018, up from 31 in 2017. The most recent U.S. strike was on Jan. 8, and several strikes in December killed 62 al-Shabab fighters, according to U.S. Africa Command.
Tuesday’s attack happened just a mile from Westgate. After the Westgate attack, security was ramped up all around Nairobi. At malls and restaurants, Nairobians now have their cars checked by guards and must go through metal detectors at entrances. The checks often seem perfunctory, however, and Tuesday’s attack will raise questions about how attackers could penetrate one of the city’s most closely guarded compounds.
In April 2015, nearly 150 people were killed and dozens of others were injured when al-Shabab militants stormed Garissa University in eastern Kenya.
Witnesses at the time said gunmen entered the university’s dormitories and opened fire, at times separating Christians and Muslims and then executing Christian students.
The standoff lasted 16 hours, and four of the gunmen were eventually killed when they detonated suicide vests.
It was the deadliest terrorist attack in Kenya since a bombing at the U.S. Embassy in 1998 killed more than 200 people.
Tuesday’s attack also comes on the third anniversary of an attack on a Kenyan military compound in which about 250 Kenyan soldiers serving in Somalia were killed by al-Shabab fighters.
Carol Morello in Washington and Paul Schemm in Addis Ababa, Ethiopia, contributed to this report.