NAIROBI, Kenya (AP) — Kenya on Wednesday is reopening the luxury hotel complex that al-Shabab attacked in January in the deadliest extremist assault inside the country in several years.

Twenty-one people were killed in the hours-long attack on the dusitD2 complex in Nairobi. Several Al-Shabab gunmen stormed the area, detonating explosives. Kenyan security forces ended the siege of the complex the following day, with all attackers killed. More than 700 people were evacuated.

The al-Qaida-linked al-Shabab in neighboring Somalia has vowed retribution after Kenya sent troops to fight the extremists in 2011. Another large-scale attack on a nearby Nairobi mall in 2013 killed 67 people.

Kenyan security forces have been praised for their quick response to the January attack, in contrast to their fumbling response to the 2013 one.