The band first heard of the atrocities unfolding in the French capital last Friday (13Nov15) when they switched on the TV news after a rehearsal for a concert in Brussels, Belgium the next day (14Nov15).
Kerr feared his brother Mark was in danger as he regularly works at the Bataclan theatre, where 89 gig-goers were slaughtered by terrorists during an Eagles of Death Metal show.
"We'd finished our production rehearsal in Brussels, came off stage and went back to our hotel feeling great," Kerr tells editors of British newspaper The Sun, "Then we switched on the TV and saw what had happened.
"We've played the Bataclan and it could have been any of us. Our crew knew people there and on a personal level, my brother Mark works in Paris as a musician.
"He plays the nightclubs of Paris every week - he's never out of the Bataclan - and his family live 20 minutes from there so I was terrified."
The Don't You (Forget About Me) singer frantically attempted to contact Mark, and eventually discovered he was safe at home.
"When I finally tracked him down he was watching Lord of the Rings with his son. It was a relief to hear they were safe," he adds.
Simple Minds are set to play a concert at Paris' Le Zenith venue on Friday night (20Nov15).
More than 130 people died in the atrocities, during which gunmen and suicide bombers targeted an international soccer match, and restaurants and bars, as well as the rock gig at the Bataclan.