"The situation is not good for now. The toll could be more than the 47 bodies that we have collected," Police Inspector General David Kimaiyo was quoted by The Standard newspaper as saying.
Kimaiyo said those confirmed dead in Sunday's attack included a police driver.
"We are yet to know if they were (Somali Islamist group) Al-Shabaab militants," he said. The attackers shouted "Allahu akbar," a witness earlier told The Standard.