A loud explosion followed by heavy gunfire was heard at 14 Riverside drive off Chiromo Road, Nairobi.
Local television showed smoke rising from the Dusit hotel, located in Westlands with panicked civilians rushing out of the vicinity.
Security officers have been deployed to Westlands in Nairobi.
According to PulseLive, the perpetrators arrived at the junction linking Chiromo Lane with Riverside Drive and remained parked for thirty minutes before the incident.
They then forced their way into the parking lot after a huge explosion, believed to have been a suicide bomber, went off at the Secret Garden Hotel.
Some reports indicate that the four may have created an entry point for more cars to access the building.
The suspected terrorists are believed to have begun shooting indiscriminately which is still ongoing in the top floors of the buildings.
Somali Islamist group Al Shabaab claimed responsibility for the attack in Kenya capital, according to Aljazeera and Katharine Houreld, East Africa Bureau Chief for Reuters.