Police said the attackers arrived on a vehicle with registration KCN 340E and another vehicle that advanced further in, police said.
They forced their way into the 14 Riverside Drive by forcing security guards at the gate to open the gate by shooting at them.
Gunfire and explosions were heard Tuesday afternoon near Nairobi's DusitD2 Hotel following a suspected terror attack.
The situation is still an active shooter situation, with evacuation ongoing. Casualties with gunshot wounds have been rushed to several hospitals in the capital.
Police sources say the attackers arrived on a vehicle with registration number KCN 340E and another vehicle that advanced further in.
They forced their way into the 14 Riverside Drive by forcing security guards at the gate to open the gate by shooting at them.
The attackers then advanced and hurled explosives into vehicles at the parking before making their way into Dusit D2 Hotel, which houses several offices and hotels.
Police units have been deployed to the scene, including the Recce Squad, Flying Squad, Anti Terrorism Police Unit (ATPU) and Bomb Squad.
The units are led by the head of the Directorate of Criminal Investigations (DCI) George Kinoti, who was also at the scene.
"Police wishes to confirm that there has been an attack incident along 14 Riverside Drive. The area has since been cordoned off and motorists are advised to use alternative routes to facilitate smooth operations of the police," the National Police Service tweeted.
3:15pm
The attack happened at 3:15pm, starting with a loud bang, before gun shots rented the air, the NairobiNews website reported.
Plumes of smoke could be seen rising from the building in Riverside Drive in the Westlands area of the city.
Images of vehicles on fire at the entrance of the hotel were being broadcast live on television stations on Tuesday afternoon.
Stay away
The police have warned people to stay away from the area as they respond to the gunshot and explosion reports.
Surrounding buildings have been evacuated under the watchful eye of armed plain-clothed and uniformed officers.
Some of the people in the nearby buildings told the Nation that they are holed up in their offices.
