A policeman and photographers take cover after hearing gun shots near the Westgate shopping center in Nairobi September 23, 2013. Thick smoke poured from the besieged Nairobi mall where Kenyan officials said their forces were closing in on Islamists holding hostages on Monday, three days after a raid by Somalia's al Shabaab killed at least 62 people. [Photo/Agencies]

NAIROBI - Kenya said it was in control of a Nairobi shopping mall that was attacked at the weekend but was still searching on Tuesday for Somali-linked Islamists believed to include Americans and a British woman who launched the assault that killed 62 people.

A burst of gunfire in the early morning broke hours of calm on the fourth day since militants of the al-Qaida-aligned al Shabaab group stormed into the Westgate center during a busy Saturday lunchtime, spraying bullets and tossing grenades.

Helicopters buzzed over the complex that is popular with foreigners and prosperous Kenyans, which al Shabaab said its militants had attacked to demand Kenya withdraw troops from Somalia where they have battled the Islamist group.

President Uhuru Kenyatta has vowed to stay the course there.

"There are still gunmen in the building," said an intelligence officer, who asked not to be named, speaking in the morning near the mall which is surrounded by troops. Asked if there were still hostages, he said: "We are not sure yet."

"We are still in there and going through every room," said one Kenyan soldier.

The Interior Ministry had hours earlier said security forces were searching for anyone left behind in the mall that was now in their control, and that all the hostages had been released.

A trickle of survivors left on Monday, but the fate of those still missing was unclear. It was also unclear how many of the militants had been killed or captured.

The government said on Monday three died and an unsourced television report on Tuesday said "six of the remaining attackers" were killed. There has been no clear official tally.

Foreign Minister Amina Mohamed told the US PBS Newshour television show that "two or three Americans" and a British woman were among the militants.

She said the Americans were "young men, about between maybe 18 and 19" years old. She said they were of Somali or Arab origin and had lived in "in Minnesota and one other place".

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