At least 14 people were killed after gunmen attacked a hotel and office complex in the Kenyan capital of Nairobi on Tuesday, reported Reuters.

Kenyan President Uhuru Kenyatta on Wednesday said all the suspected militants have been killed after an almost 20-hour siege, AFP reported. It was not clear how many attackers were involved in the incident.

“I can confirm that... the security operation at Dusit complex is over and all the terrorists eliminated,” Kenyatta said in a televised address. “As of this moment, we have confirmation that 14 innocent lives were lost to the... terrorists, with others injured.”

Kenyatta said 700 civilians were rescued during the siege, but did not clarify if people were still hiding in the complex.

The Somalia-based militant Islamist group al-Shabab has claimed responsibility for the attack, which took place at the 14 Riverside Drive complex. It began around 3 pm (5.30 pm Indian local time) on Tuesday, BBC reported. Kenyan police chief Joseph Boinnet told BBC that gunmen threw bombs at vehicles in the car park before entering the lobby of a hotel, where one person blew himself up.

Around 8 pm, 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 said. “Terrorism will never defeat us.” However, gunfire was still reportedly heard from the area an hour later.

An unidentified first responder said identification papers indicated that 11 people who died in the attack were Kenyan, one was American and one British. Two people did not have an ID card on them.

United States Ambassador to Kenya Bob Godec condemned the attacks and offered US assistance, CNN reported. He confirmed that all embassy personnel were safe. UN Secretary-General Antonio Guterres expressed “his solidarity with the people and government of Kenya”.

Al-Shabab is a militant group that opposes the Somali government which also carries out attacks throughout East Africa. Kenya is part of a peacekeeping operation that supports the Somali government against the al-Shabab.