Westgate attackers may have escaped, New York police report says

A report issued on Tuesday by the New York City Police Department gives a much different account of the Westgate Mall attack than what has been presented by Kenyan authorities.

Only four men appear to have carried out the massacre -- not 15, as Kenyan officials speculated -- and all of them may have gotten away, suggests the report, which was released to private security personnel in New York.

"It is unknown if the terrorists were killed or escaped the mall," the report says. "A major contributing factor to this uncertainty was the failure to maintain a secure perimeter around the mall."

Contrary to Kenyan officials' statements during and following the attack, the New York police report says the terrorists did not hold hostages inside the mall, nor did they create a smokescreen by setting fire to mattresses.

Security video recovered after the onslaught indicates that the shooters were not "interested in taking any hostages," according to the NYPD account. "They only appeared interested in killing a broad spectrum of people."

(Read: How Kenya took the fight to al-Shabaab)

After exploding three grenades upon entering the mall, the killers used AK-47 assault weapons in single-fire mode to shoot their victims, according to the findings of an NYPD team sent to Nairobi as part of a US anti-terrorism task force that investigated the attack.

The report credits private security guards at the mall with helping many people reach safety.

CHAOTIC RESPONSE

But it depicts a chaotic response on the part of Kenyan authorities.

Law enforcement personnel were slow to arrive at the scene, with the first tactical team reaching the mall about 90 minutes after the start of the attack at about 12:15 pm on September 21, the report says. The Kenyan tactical team did not actually enter the mall until 3:00 pm, the NYPD adds.

The first set of police officers inside Westgate did not have official markings, and were fired on by Kenyan soldiers, the report states. The officers also lacked basic equipment such as bulletproof vests, radios and handguns, the NYPD found.

Kenyan emergency responders "had no idea what the mall looked like internally,” and did not know how to access the mall's closed-circuit television system, the assessment adds.

The attackers disabled or tilted some of the system's cameras to conceal their whereabouts. But footage seen by the NYPD investigators does show four gunmen gathered in a supermarket storage room where they apparently remained for six hours, praying and tending to one of their number who had been shot in the leg.

The terrorists may have slipped out of the mall 12 hours after the start of the attack, the NYPD account speculates.

The siege by Kenyan police and army units went on for two more days.

Lt Detective Commander Kevin Yorke, who prepared the report, told journalists on Tuesday that he is sceptical of Kenyan authorities' claims that the attackers died when explosions caused parts of the mall to collapse.

Yorke added that he did not know why that collapse occurred. But he said the Kenyan military may have used rocket-propelled grenades and anti-tank missiles during the siege, with consequent fires inside the mall weakening the structure.

The NYPD detective commander added that there is "significant" physical and video evidence that some Kenyan military personnel looted the mall.