Joshua Hakim saw gunmen, some of whom looked to be teenagers, strapped with ammunition belts. They were carrying AK-47 assault rifles. "They were firing indiscriminately, they shot a lot of people," theguardian.com quoted him as saying Sunday.
During a lull in the firing, the gunmen spoke in Swahili for Muslims to identify themselves and leave.
Hakim covered the Christian name on his ID with his thumb and approached one of the attackers. He showed the plastic card.
"They told me to go. Then an Indian man came forward and they said, 'What is the name of Muhammad's mother?' When he couldn't answer they just shot him," he said.
It was not clear from the media report whether the Indian was injured or fatally shot.
The hostage crisis that began Saturday has left at least 68 people dead and more than 175 injured.
Mumbai Roundup: 9 incidents that took place this week
Photos: Ajay Devgn, Parineeti, Tabu at 'Golmaal Again' trailer launch
Photos: Dipika Pallikal Karthik oozes oomph in bikinis and sarees
Photos: Kareena Kapoor Khan's grand birthday bash
Photos: 'Dangal' girls Sanya Malhotra, Fatima Sana Shaikh's dinner outing