Seems like you either trigger the explosive vest, or get gunned down beforehand, but not both.
Having read the article, I believe the most descriptive phrase is that which calls the bombing “an increasingly confusing situation.” Central fact seems the the bomber set off his vest bomb and then was shot and killed. He also may have had a backpack or a suitcase bomb.
Maybe he wasn’t wearing the vest....
I heard he triggered a small bomb in his back pack and was about to ignite his suicide belt when he was drilled like Swiss cheese.
Best insight of the day.