The terrorists who attacked the Westgate shopping mall in Kenya's capital Nairobi Saturday seemed to have taken lessons from a first rate action movie, given the magnitude of human casualty, panic and general malaise.

Heavily armed assailants stormed into Westgate shopping mall in Nairobi at noon and rained terror on shoppers, workers and onlookers, Xinhua reported.

Eye witnesses told journalists that the well-coordinated terrorist attack was carried out by about 10 hooded men.

"It was a scene from hell, as the frightened and wounded shoppers scattered everywhere in search of safety. Everyone cowed in fear as the powerful sound of gun fire reverberated inside the mall," Xinhua cited a frightened shopper's tweet.

Somalian militant group Al Shabaab has claimed responsibility for the vicious attack, which has so far claimed at least 59 lives and left 175 others injured.

Survivors recounted how the Supermarket aisles were a sea of humanity slightly before the attacks.

"A conservative figure of 5,000 were inside the mall. The world came tumbling before our eyes, as the assailants shot randomly at anyone in sight. The wailing and anguish among the wounded will never be deleted from our memory," an anonymous survivor tweeted.

Courageous survivors who spoke to the media gave a blow-by-blow account of how it all started, as heavily armed men in fatigue jackets alighted from a small vehicle and stormed into the mall.

"These men covered their faces with black hoods and their actions thereafter turned the entire place upside down," Daniel Musili, a supermarket attendant, said.

"The sound of grenades and gunfire could shatter our eardrums. We lay flat on our bellies and the lucky few crawled their way out through narrow openings," he said.

Frightened survivors trapped inside the mall tweeted about their predicament while others made frantic calls to relatives, friends and colleagues to update them on the progress of rescue efforts.

"The sight of mothers crawling as they tightly held their babies was gory. To make matters worse, even able bodied individuals who survived the terror were too frightened to lend any help," a Kenyan print journalist said.

He counted dozens of wounded survivors crawling on the driveway to safety while ambulance sirens echoed from far distances as rescue operations reached a crescendo.

The social media was abuzz with activity soon after the terrorist attack.

"Westgate under siege, hard to tell the number of the dead and injured. The situation fluid, but superb response from security forces is quite reassuring. Let's be patient as more information about the attacks filter in," tweeted an individual using an acronym, JK.

Minutes after the terrorist attack at the mall, a rescue mission comprising security forces, paramedics and volunteers mounted a major operation to save lives and calm the situation.

Senior government officials oversaw the rescue mission while paramedics were on standby to attend to wounded survivors.

Kenya's interior ministry gave real-time updates of the rescue efforts while reassuring the public that the situation was under control.