The shooting began around 10:45 p.m. on a block of old tenements and industrial buildings in Newark.

Witnesses heard what they mistook for fireworks and had no idea what was going on until the police showed up. One man was dead on the ground in front of a home on Brunswick Street. Two wounded people were in a nearby parking lot. Another two got to the hospital on their own.

Mass shooting or just a random act of violence in New Jersey's largest city?

In the unsettled world of tracking gun violence -- an issue that once again erupted with deadly consequences with the recent terror attack in San Bernardino -- the number of mass shootings in the United States is an inexact statistic.

Experts haven't all agreed on an accepted definition of what constitutes a "mass shooting."

It's all in the counting, said James Alan Fox, a Northeastern University professor and author of books on gun violence and mass shootings.

To Fox, mass shootings are events where at least four people, not including the shooter, are shot and killed -- a metric used by the FBI since at least 2005. Congress in 2013 lowered that number to three killed in events where federal assistance is needed.

In more than half of those events, he noted, the killing is done by an individual toward family members. The least common event is the public shooting like San Bernardino.

But others think that definition grossly understates the true measure of gun violence in the United States, sparking recent news accounts in the wake of the San Bernardino terror attack that put the number of mass shootings this year alone at more than 350.

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That number -- 353 as of Thursday -- came from shootingtracker.com, a crowd-sourced database created by a group of gun-control advocates on the online bulletin board site Reddit.

The difference is shootingtracker.com, which compiles data reported by news media around the country, counts any event where four people or more are shot, regardless of whether anyone is killed. The site counts not just random attacks, but also gang shootings and everyday crimes, including domestic incidents.

Fox says the online database confuses the public by mixing shootings and killings.

"The unsophisticated reader assumes there are 355 events of loads of killings," he said of the shootingtracker.com site. "That's not the case."

Fox doesn't deny that shootings with fewer than four killed are tragic, but said it obscures the point. It's why, for example, police agencies break out homicides from attempted homicides in their statistical counts, he said.

"There are slightly more than 20 mass killings a year on average," said Fox. The data, he said, shows "no trajectory. It's an up and down oscillation the last few decades."

According to shootingtracker.com, New Jersey has suffered from mass shootings 11 times this year.

The incident that involved the most victims, according to shootingtracker.com, was the still-unsolved July 1 incident on Brunswick Street in Newark, that left Bashir Edwards dead and four others wounded in Newark. Keyon Diggs, one of the wounded, died later from his injuries.

Three other Newark shootings are listed on shootingtracker.com, with four shot in each case. In one of those shootings, 15-year-old Shakeem Woodson, an innocent bystander who was attending an annual motorcycle event, was killed amid crossfire by four teens who had a dispute.

Two shootings of four occurred in Jersey City. Others occurred in Paterson, Trenton, Camden and East Orange, according to shootingtracker.com and NJ.com records. Motives were unclear, according to the media accounts cited by shootingtracker.com.

None of the 11 New Jersey killings on the shootingtracker.com database would fit the FBI's definition of a mass shooting. The closest would be the September killing of Amanda Morris and her two young boys, Brandon and Brian Beharry in their Long Branch home by the boys' father, Lyndon "Shane" Beharry. He then set fire to their house and turned the gun on himself.

Still, the dispute about how to count the nation's mass shootings obscures the real toll in the United States, said Eugene O'Donnell, a professor at the John Jay College of Criminal Justice in New York City. Whether shootings or mass killings are counted, he said, the carnage is "blindingly obvious."

Discussions about gun violence too often break down into liberal-conservative arguments, O'Donnell said.

"Whatever your frame of reference is," he said, "the country has an enormous gun problem."

Tim Darragh may be reached at tdarragh@njadvancemedia.com. Follow him on Twitter @timdarragh. Find NJ.com on Facebook.