(Bloomberg) -- Kenyan forces hunted for gunmen who stormed an upmarket hotel and office complex in the capital, reportedly killing at least three people in the first apparent major attack by an al-Qaeda affiliate in the East African nation in almost four years.

The attack on 14 Riverside Drive in Nairobi began 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, police Inspector-General Joseph Boinnet said Tuesday in a televised briefing.

“Six out of the seven floors of the hotel building have been secured,” Boinnet said. “Operations continue to secure the remaining buildings in the complex.” He added that “a number of guests suffered severe injuries.”

Al-Shabaab, an affiliate of al-Qaeda based in neighboring Somalia, claimed responsibility on Radio Andalus, a broadcaster that supports its insurgency. If confirmed, it would be the group’s first significant assault in Kenya since it raided a university campus in Garissa county in April 2015, killing at least 147 people.

The Star, a Nairobi-based newspaper, reported three people were killed. Live TV footage showed vehicles on fire near the entrance to the complex and police officers evacuating people from the scene. Boinnet said there’d been considerable progress in containing the situation.

The 14 Riverside complex, located on the outskirts of central Nairobi and 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. The country, which has East Africa’s largest economy, is a regional hub for international commerce.

Tuesday’s incident evokes memories of a raid by al-Shabaab on an upmarket Nairobi shopping mall in September 2013 in which at least 67 people died. On Monday, a Kenyan court ordered three suspects to be tried for their involvement in the attack, the Standard newspaper reported.

Al-Shabaab has been fighting in war-torn Somalia since about 2006 in a bid to impose its version of Islamic law. For a time it controlled much of the capital, Mogadishu, until it was ousted by Somali and African Union forces in 2011.

Tuesday marks 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 given a death toll for the raid.

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