The Jain community, whose small Indian religion upholds non-violence as a sacred principle, opened their doors at the onset of the attack on September 21 claimed by Somalia's Al-Qaeda-linked Shebab group.
As the crackle of gunshots filled the air, the Oshwal religious centre just 100 metres away was a haven where survivors, relatives, security forces and journalists were sheltered, treated, counselled and fed.
"We have a lot of space and numerous parking places," said Bhupendra Shah, a senior member of the Visa Oshwal community.
"We sent emails to request help, and donations started to arrive on Sunday morning," said Shah.
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Within hours the Jains mobilised like an army and tapped into their formidable economic power.
Families brought gallons of juice freshly squeezed at home, a sporting club donated eight vans packed with food, an industrial bakery and a top retail chain gave tonnes of bread and water bottles.
The Jains have only 12,000 members in Nairobi, a city of four million with a large population of Indian descent, but among them are the CEOs of Nakumatt, East Africa's retail giant, and other top companies.
Three times a day, the red vests of the Red Cross, the green ones of the St John ambulance service, the camouflage gear of the elite forces battling the mall attackers, mingled in the queue.
Police officers bristling with assault rifles and journalists with cameras also got in line for a plate of food, taking a short break as the siege dragged on.
Serving this exhausted crowd on the front line of one of the worst attacks in Kenya's history were 400 Jain volunteers working in shifts to welcome their visitors.
The Oshwal centre also made space available to teams offering psychological counselling to traumatised survivors and bereaved families, or helping people to report a missing person.
At least 67 people, including children, are so far confirmed to have been killed in the attack, that also left dozens wounded and 61 people are still reported missing.
"Jain is one of the oldest religions in the world," Shah said. "Our religion says 'do not kill, don't have anger', 'respect any form of life'.