(Bloomberg) -- Kenyan security forces ended an attack on an office complex in the capital by suspected Islamist militants that left 14 people dead, President Uhuru Kenyatta said.

All of the assailants were killed, the president said in a televised address Wednesday in Nairobi.

“We will seek out every person that was involved in the planning, funding and execution of this heinous act,” Kenyatta said. “We are grieving as a country this morning, and my heart and that of every Kenyan goes out to the innocent men and women violated by senseless violence.”

The Somalia-based al-Shabaab militant group claimed responsibility in the first apparent major attack by the al-Qaeda affiliate in the East African nation in almost four years.

The assault began Tuesday afternoon with an explosion targeting three vehicles in the parking lot and then a suicide-bombing in the foyer of a Dusit Hotels & Resorts Co. outlet, according to police. Sporadic gunfire continued into early Wednesday as Kenyan authorities said they were securing the hotel. The local Star newspaper reported shortly before Kenyatta’s speech that all six assailants were dead.

Militants’ Claim

Al-Shabaab said it killed 50 people in the attack, according to Radio Andalus, a broadcaster that supports its insurgency. The group didn’t say how it obtained the figure. The Islamists’ last significant assault in Kenya was a raid on a university campus in Garissa county in April 2015 that killed at least 147 people.

The extremists have vowed to keep up attacks as long as Kenya maintains soldiers in Somalia, where it’s part of an African Union mission. A survivor of the attack who gave his name as Reuben told local Citizen TV that he heard the gunmen accuse Kenya of killing “our people in Somalia” and “ruining our way of life.”

Previous attacks, including a raid on an upmarket shopping mall that left at least 67 people dead, have curbed tourism -- a key industry that’s one of Kenya’s main generators of foreign exchange. On Monday, a Kenyan court ordered three suspects to be tried for their involvement in the 2013 attack, the Standard newspaper reported.

The 14 Riverside complex, popular with business travelers and Kenya’s elite, hosts restaurants, banking facilities and offices for companies including LG Electronics Africa, Pernod Ricard SA and Dow Chemicals East Africa Ltd.

Security Efforts

“Throughout the breadth of Kenya and in our immediate neighborhood, multiple security efforts are under way to detect, deter, disrupt and defeat any terrorist operatives or groups,” Kenyatta said. “In the coming days and weeks we shall continue the never-ending work to strengthen our systems.”

Al-Shabaab has been fighting in civil war-torn Somalia since about 2006 in a bid to impose its version of Islamic law. For a time the group controlled the capital, Mogadishu, until it was ousted by African Union forces in 2011 but it still regularly attacks Somali government facilities and civilians. Members also carried out bombings in Uganda in 2010 and Djibouti in 2014.

Tuesday marked the third anniversary of an al-Shabaab attack on an African Union base in Somalia in which the extremists said dozens of Kenyan soldiers were killed. Kenya’s government has never said how many people died.

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