As Vice President Joseph Biden met today with gun rights advocates about the White House plan to stop gun violence, Midwestern mayors and law enforcement authorities convened in Minneapolis to exchange ideas on stopping the illegal flow of guns that harms thousands of people in urban areas.

Mass shootings in Newtown, Conn., Aurora, Co., and Virginia Tech in recent years are “high hazard, low probability” events that bring people together to talk about gun violence, said Milwaukee Police Chief Edward Flynn.

But in America’s cities, “there is a slow motion mass murder taking place every year,” he said. “This violence is highly concentrated, highly localized, and it’s a significant part of the violence problem in America” that must be addressed with different solutions than those being discussed to prevent the December elementary school shooting in Newtown that killed 20 children and six educators.

Convened by Minneapolis Mayor R.T. Rybak and Milwaukee Mayor Tom Barrett, the Midwestern Regional Gun Summit brought together mayors, police chiefs, sheriffs and prosecutors from at least five states. While much of the summit was closed to the media, officials held a news conference to affirm their commitment to reducing gun violence and to call on Washington to strengthen laws and the main agency that enforces them.

Rybak criticized federal legislation, known as the Tiahrt Amendment, that for years has restricted access to gun trace data showing where illegally obtained guns come from.

He questioned why some of the statistics on Minneapolis and Milwaukee crime guns presented Thursday morning were more than a dozen years old.

“When I’m at a murder scene, when I’m standing with the mother over the body of her dead child, she deserves to know where that gun came from,” he said.