"One man said he saw two armed men with scarves on their head and bandoliers of bullets", Medic told Reuters, as gunfire echoed in the background, more than two hours after the attack began.
The photographer saw five bodies slumped over tables on a restaurant terrace in the complex, which was hit in an attack claimed by Al-Shabaab Islamists.
Somalia's al-Shabaab are a militant Islamist group that opposes the Somali government but has also carried out attacks throughout East Africa.
Interior Minister Fred Matiang'i had said at 11 p.m. that all buildings had been secured and scores of people evacuated from the scene.
Eight hours after the assault began at Nairobi's upscale 14 Riverside Drive complex, a burst of gunfire was heard in the area, suggesting the situation was not yet under control.
Police said the gunmen blew up a auto that had explosives inside. "My colleagues were running everywhere", said another man who did not give AP his name.
He told AFP news agency: "We have no idea what is happening".
'We can do better': Tom Cruise announces two new Mission: Impossible movies
The next two films , the seventh and eighth in the franchise, are expected to shoot back-to-back. Not such an impossible mission , as it turns out.
The suspected terror attack is unfolding at the complex, which houses a large hotel known as DusitD2, along with several banks and offices.
However, a Kenyan police officer who spoke on condition of anonymity because he was not authorized to talk to the media said that bodies were seen in restaurants downstairs and in offices upstairs, but "there was no time to count the dead".
Cars burn at the parking lot during an ongoing gunfire and explosions in Nairobi, Kenya.
Three cars were ablaze by the entrance and a picture of the hotel grounds on Twitter showed what appeared to be a human a leg lying on the path.
In a statement, Kenya's police said "armed criminals are holding up in the hotel and specialist forces are now currently flushing them out".
Police spokesperson Charles Owino earlier said that "we have sent officers to the scene, including from the anti-terrorism unit, but so far we have no more information".
What appears to be plainclothes security forces are seen slowly working their way toward the scene, guns in hand.
Tuesday marks the third anniversary of an al-Shabaab attack on an African Union base in Somalia in which the assailants said dozens of Kenyan soldiers were killed.
Son accord balayé, Theresa May est désavouée par le Parlement — Brexit
Les débats ont repris vers 14h, heure de Luxembourg, et s'achèveront en fin d'après-midi avec une intervention de Theresa May . La Première ministre avait reçu le soutien de 200 des 315 députés appelés à se prononcer.
Kenyan television featured appeals for blood from local hospitals and showed police cordoning off the route to ensure vehicles could move quickly.
Multiple injured victims were still trapped inside an upscale Kenya hotel complex almost 11 hours after the attack began, an emergency responder said. The attack and ensuing siege lasted around four days.
"It is bad. What I have seen is awful", said Charles Njenga, who ran from a scene of blood, broken glass, burning vehicles and pillars of black smoke.
Despite the repeated attacks, the Kenya-Somalia border remains porous, with al-Shabab extremists able to easily bribe their way across, according to a United Nations panel of experts.
Al-Shabab has vowed retribution against Kenya for sending troops to Somalia since 2011.
Officials, however, gave no details of the death toll.
April 2015: Al-Shabab launched an assault on Garissa University College in Kenya, killing 148, mainly students.
L'ex-président ivoirien Gbagbo acquitté par la Cour pénale internationale
L'ancien président âgé de 73 ans et son ex-ministre entendent bien continuer à jouer en un rôle politique dans un pays toujours très divisé.