I don't know about Bobigny specifically, but it is in the department of Seine-Saint-Denis, which wikipedia (yeah, I know, but politically incorrect facts on wikipedia are usually reliable) suggests has Islam as its most practiced religion, and which also includes Clincy-sous-Bois, where the two Muslim "youths" managing to get electrocuted while fleeing the police set off the big riots in 2005
We took the subway to Saint-Denis when we were there about 8 years ago. Got out, looked around, yikes! The church of Saint Denis, where all the French kings are buried, had just closed. The town was very dicey, we left quickly. If it was there, it would be more suspicious, unless they were singeing goat innards or something and used the gas wrong.