'No time to count the dead': Nairobi attackers still at large

Police in the Kenyan capital of Nairobi are searching an upscale hotel complex for the perpetrators of an attack carried out earlier on Tuesday, when the building was rocked by an explosion.

Heavy gunfire later reverberated through the complex as bystanders fled the scene.

Al-Shabaab - the Somalia-based extremist group that carried out the 2013 Westgate Mall attack in Nairobi that left 67 people dead - claimed responsibility and said its members were still fighting inside.

"We are aware that armed criminals are holing up in the hotel, and special forces are now currently flushing them out," said Kenya's national police chief, Joseph Boinnet, described the assault as a suspected terror attack.

He did not confirm any deaths and or say how many were wounded.

A Kenyan police officer who was among the first on the scene of the attack says "there was no time to count the dead but it is true that there are people who are dead."

The officer said some bodies were in restaurants downstairs and that colleagues saw others in offices upstairs.

The attack came a day after a magistrate ruled that three men must stand trial on charges they were involved in the Westgate Mall siege. A fourth suspect was freed for lack of evidence.