On Saturday, the Somalia-based al Shabab terror group used deadly force to take control of an upscale mall in Nairobi, Kenya. As many as 16 assailants lobbed grenades and fired automatic weapons into a crowd of weekend shoppers, killing at least 68 people and taking an unknown number hostage. The siege continued into Monday as government forces battled the terrorists for control of the building.

The images of shoppers-turned-survivors crawling, ducking, and sprinting for safety, often doing whatever they could to help petrified strangers do the same, shows how terrifying this ongoing ordeal really is. Here, a selection:

A woman who had been hiding during the gun battle runs for cover after armed police (behind) enter the mall. (AP Photo/Jonathan Kalan)

A mother and her children hide from gunmen inside the Westgate Shopping Centre. Sporadic gun shots could be heard for hours after the assault started as soldiers surrounded the mall and combed the building, hunting down attackers shop-by-shop. (REUTERS/Siegfried Modola)

People scramble on all fours and crawl on their stomachs to take cover during the shooting spree on Saturday. (REUTERS/Goran Tomasevic)

Civilians are escorted out of a section of the shopping center by police. (REUTERS/Siegfried Modola)

A man helps a child find safety within the mall. (REUTERS/Goran Tomasevic)

A police officer holds a gun to provide cover for customers running out of the mall, just as more shooting erupted. (REUTERS/Noor Khamis)

A wounded woman and young girl react to the violence. (REUTERS/Goran Tomasevic)

Medics take cover behind a large tree as gunfire and explosions are heard from the mall on Monday. Multiple large blasts rocked the building on the third day of the hostage siege. (AP Photo/ Jerome Delay)