A fatal mass shooting in Glendale was isolated, police said. And it's one of dozens in the U.S. so far this year. But reputational concerns remain.

NBC affiliate KPNX of Phoenix reported that the restaurant El Camarón Gigante was holding a Cinco de Mayo party at the time.

Security at El Camaron Gigante kicked out people who started fighting inside the venue, a Glendale police spokesperson said during a May 5 news conference. Once in the parking lot, the individuals started firing gunshots, police said.