Gunfire rang out again at the upscale hotel complex at 14 Riverside at around 6 a.m. (0200 GMT) and went on to erupt sporadically, a first responder told Reuters.
"The area around 14 Riverside Drive is a Crime Scene ... under an active security operation," police said in a message on Twitter.
The attack, by at least four gunmen, began shortly after 3 p.m. on Tuesday with an explosion in the parking lot and then a suicide bomb blast in the foyer of the dusitD2 Hotel, police said.
Somali militant group Islamist group al Shabaab claimed responsibility.
Many of the victims had been dining in the Secret Garden restaurant and lay slumped at their tables, photos viewed by Reuters showed.
Eleven Kenyans, an American and a Briton were among the casualties, morgue staff said. Two victims had not been identified.
Blasts and shots had punctuated the night, undercutting assurances from the interior minister late on Tuesday that the scene had been secured and complicating the rescue of scores of people still trapped.
Some of those trapped got messages out begging for medical help.
At least two groups of people remained in the hotel and business complex at nearly 7 a.m., a first responder told Reuters.
Families who had gone to the Chiromo morgue seeking loved ones were told they could not view the bodies until a forensic investigation had been performed, provoking grief and anger.
The family of one 35-year-old Kenyan collapsed in the courtyard upon hearing a body had arrived with his identification papers.
"He is gone, he is gone," the father repeated into his phone as his mother wrapped a shawl around herself and wept.
Another family arrived, demanding to see whether their relative was there but were told only police had access.
As they argued, an elderly couple arrived in silence, bringing a freshly pressed suit to dress their son.
Outside the morgue, two Red Cross ambulances waited, their drivers asleep inside. They would go to the complex to retrieve casualties once it was safe, morgue staff said.At 7 a.m. (0400 GMT), heavy gunfire rang out again