NAIROBI - Kenyan troops and elite units joined police fighting gunmen in Nairobi's upmarket Westgate shopping mall, an AFP correspondent at the scene said.
The gunmen sprayed gunfire, before holing themselves up in the complex with hostages. Thirty people are confirmed to have been killed, a senior police official said. The Red Cross said another 50 wounded in the attack.
"The death toll is now standing at 30, this includes those who have died at the scene and at the hospital," the official told reporters.
Troops moved around and inside the shopping centre, where unidentified gunmen launched an assault with automatic weapons and grenades shortly before midday.
A security source at the scene said Kenyan special forces were involved in operations to secure the mall and evacuate trapped staff shoppers.
Military and police helicopters were also flying overhead.
Witnesses said the gunmen spoke Arabic or Somali and executed shoppers, in what appeared to be the worst attack in Nairobi since an Al-Qaeda bombing at the US embassy killed more than 200 in 1998.
As security forces were trying to secure a multi-screen cinema complex on the mall's top floor, a police source said it had been confirmed that the attackers were holding at least seven hostages.
A policeman carry's a baby to safety after masked gunmen stormed an upmarket mall and sprayed gunfire on shoppers and staff
An AFP reporter said she saw at least 20 people rescued from a toy shop. Dozens of wounded, some of them bleeding children, were stretchered away from the mall.
A shop manager who managed to escape said at one point "it seemed that the shooters had taken control of all the mall".
"They spoke something that seemed like Arabic or Somali," said a man who escaped the mall and gave his name only as Jay. "I saw people being executed after being asked to say something."
Shocked people -- black, white and Indian -- could be seen running away from the Westgate centre clutching children while others crawled along walls to avoid stray bullets.
'I saw people being executed'
The mall -- which has several Israeli-owned businesses, is a hub for Nairobi-based Westerners and one of the foremost symbols of Kenya's affluent classes -- has long been considered a potential terror target.
Kenneth Kerich, who was shopping when the attack happened, described scenes of panic.
"I suddenly heard gunshots and saw everyone running around so we lied down. I saw two people who were lying down and bleeding, I think they were hit by bullets," he said.
"Initially we thought it is police fighting thugs. But we could not leave until when officers walked in, shot in the air and told us to get out."
An eyewitness who survived the assault by gunmen said he saw the body of a child being wheeled out of the mall.
"The gunmen tried to fire at my head but missed. At least 50 people were shot. There are definitely many casualties," mall employee Sudjar Singh told AFP.
"I saw a young boy carried out on a shopping cart, it looked like he was about 5 or 6. It looked like he was gone, he was not moving or making any noise."
Elite units run to the crime scene early today. Photo by AFP
Vehicles riddled with bullet holes were left abandoned in front of the mall as the Red Cross appealed for blood donations and police instructed residents of the Westlands neighbourhood to stay away.
"Our officers are on the ground carrying out an evacuation of those inside as they search for the attackers who are said to be inside," Inspector General of Police David Kimaiyo said.
"We have managed to evacuate some people to safety. We urge Kenyans to avoid the area as we pursue the thugs," Kenya's interior ministry said on Twitter.
The Westgate mall, which opened in 2007, has restaurants, cafes, banks, a large supermarket and a cinema that attract thousands of people every day and have made it a Nairobi landmark.
It is popular with the large expatriate community living in the residential neighbourhoods around it, including with foreign staff from the United Nations, which has its third largest global centre nearby.
Security agencies have regularly included the Westgate shopping centre on lists of sites they feared could be targeted by Al Qaeda-linked groups.
The Somali insurgents from the Shebab group have repeatedly threatened to strike at the heart of Kenya in retaliation for Nairobi's military involvement alongside the government they are trying to overthrow.