Police are calling it a terrorist attack.
There are reports of fatalities and injuries.
The complex houses the Dusit hotel and other offices.
Witnesses say they saw 4 armed men enter the complex.
Several vehicles were burned in the blast and people were being rushed, even carried, from
In 2013 al-Shabab extremists burst into the luxury Westgate shopping center, hurling grenades and starting a days-long siege that left 67 people dead.
Al Shabaab is also claiming responsibility for this latest attack.