13 mass shootings took place over this weekend alone, leaving 18 dead and 72 injured

• At least 13 mass shootings occurred in the US between Friday evening and Sunday evening.
• So far, 18 victims have died and another 72 have been injured in incidents across the US.

At least 18 people were killed, and 72 more were injured this weekend in mass shootings across the US.

The 13 incidents come in the wake of several high-profile shootings over the last two weeks that have reignited the national debate around gun rights and safety.

Insider has based its tallies on data from the Gun Violence Archive non-profit group and multiple media reports. The Gun Violence Archive defines a mass shooting as an incident in which at least four victims were shot, excluding any shooters.

At least five of the shootings this weekend took place in a public area, while at least three were carried out at graduation parties. Of all 13 incidents, the youngest reported injured victim is 12 years old, while the youngest fatality was a 14-year-old girl.

Here's what we know about the 13 mass shootings over the weekend.

Victims were run over by fleeing cars in Chattanooga, Tennessee

Fourteen people were hit by gunfire at a nightclub early Sunday, and three more were struck by vehicles as people fled the scene, according to Celeste Murphy, Chattanooga's police chief, per The Associated Press.

Murphy said that two people died from gunshot wounds, and another died after being hit by a vehicle.

According to Murphy, 16 of the victims were adults, and one was a juvenile; several of them are still in critical condition.

Authorities said that multiple shooters were involved in the incident and that an investigation into the shooting is ongoing, per the AP.

It's not yet clear what the motive for the shooting was, but police believe it was an isolated incident "in which one or more of the victims were targeted," according to CNN.

Panic on a public street in Philadelphia, Pennsylvania

Multiple shooters opened fire at a popular entertainment district in the South Street area of Philadelphia on Saturday evening, authorities said, according to multiple reports.

At least three people have died, and 11 more were wounded, police said, per CNN.

"At this point, we don't know whether or not the altercation that took place was between a group of individuals, or if this was tied to another group or affiliation," said Philadelphia Police Commissioner Danielle Outlaw, per the outlet.

Five guns were used in the incident, Outlaw said. One of the shooters was wounded by police and escaped, while another is thought to be one of the persons killed, the commissioner added, per CNN.

The deceased victims were identified as a 34-year-old Gregory Jackson, 27-year-old Alexis Quinn, and an unnamed 22-year-old man, NBC10 Philadelphia reported.

Among the surviving victims are two 17-year-old girls and one 17-year-old boy, according to NBC10 Philadelphia, citing Outlaw.

Teenage girl dies at a strip mall in Phoenix, Arizona

A 14-year-old girl was fatally wounded at a strip mall in Phoenix, Arizona, where 100 people had gathered for a party before fighting broke out early Saturday morning, police said, per USA Today.

The fight eventually turned into a series of shootings in the building and spilled out onto the parking lot and street, the outlet reported, citing local police.

"Many rounds were shot into this crowd of people as everyone fled the area," police said, per USA Today.

Apart from the teenage girl — who died of her wounds in the hospital — two women, five men, and a teenage boy were shot and injured, USA Today reported. The two women are currently in critical condition, per the outlet.

The shooter has not been caught, according to Fox10 Phoenix.

Six children shot in Summerton, South Carolina

An outdoor graduation party on Saturday evening was interrupted by shooters in two cars who pulled up to the venue and opened fire on attendees, according to a statement from the Clarendon County Sheriff's Office.

Authorities said that a total of 60 to 70 rounds were fired before the shooters left and drove south on St. Paul Highway. The statement added that it is unclear if anyone in the crowd returned fire at the shooters.

The sheriff's office said a 32-year-old woman died of gunshot wounds, and another seven people were injured. Among those hurt were a 12-year-old, a 13-year-old, a 14-year-old, two 15-year-olds, and a 17-year-old.

"It is not sure whether shots were fired at specific persons or just randomly into the crowd," the statement read.

Police believe this was a gang-related incident stemming from previous drive-bys in the county.

50 shots fired at graduation party in Chester, Virginia

Another graduation party on Friday night ended in violence, leaving a 20-year-old man fatally shot and seven others injured, police said, per The AP.

Authorities said two separate fights had happened at the mostly-outdoor party before police received calls about the gunfire, The AP reported.

Chesterfield County Police Maj. Brad Badgerow said at a news conference that police found 50 casings fired by four different calibers, the outlet reported.

"Whether that means it was four people shooting — I can't tell you that," Badgerow said, per The AP. "But it looks like there were at least four different weapons that were fired."

Two of those injured were struck by a car as the crowd fled the shooting, and the victims' ages range from 16 to 21, the AP reported.

Teens injured at a graduation party in El Paso, Texas

Five teenagers were hospitalized, and two are in critical condition following a shooting at a high school graduation party early Saturday in Socorro, a town near El Paso, Texas.

Those at the party said fighting had broken out between two groups, police said, per the AP.

Gunfire in downtown Grand Rapids, Michigan

A man was killed, and three other adult males were injured, after gunfire erupted in downtown Grand Rapids early Sunday.

According to local outlet MLive, police have not released the identities or ages of the victims.

An MLive reporter heard 10 shots being fired, the outlet reported.

Nightclub shooting in Mesa, Arizona

Two people were found dead in a parking lot and two others were injured after a shooting at a nightclub early Sunday morning, police said, per CBS affiliate AZ Family.

Authorities are still working out the events that led up to the shooting, although officers said they saw someone speeding away from the venue as they arrived at the scene, per the outlet.

One of the injured persons is a security guard, police said, per AZ Family.

Five shootings in residential areas; 21 victims in total

On Saturday evening, 19-year-old Cleveland Raines was killed in a shooting at an abandoned house in Macon, Georgia, according to the Bibb County Sheriff's Office. Three other victims, 19-year-old Ralph Hughes, 23-year-old Jarvis Devon Hill, and 22-year-old Alizya Sinclair, were injured, authorities said.

Police have not said why the victims were at the abandoned house, and an investigation is still ongoing.

In Omaha, Nebraska, 31-year-old Pierre R. Hightower was found dead at the scene of a shooting on Friday night, while three other victims were sent to hospital, ABC affiliate KETV Omaha reported.

Nassau County Police are also investigating a Saturday night shooting in Hempstead, New York, where a 19-year-old male was killed and three other men, aged 23, 31, and 35, were hospitalized with gunshot wounds to the ankle and thigh, NBC News reported.

Meanwhile, in Ecorse, Michigan, four people were shot early Saturday in an incident reportedly involving a party bus, per the Gun Violence Archive, which cited a Facebook account that monitors dispatch radio. There have been no reported deaths so far.

In Saginaw, Michigan, two men were pronounced dead at the scene of a shooting and one woman died of her wounds at the hospital, the AP reported. Police responded to the shooting on early Sunday, the outlet wrote.

Another two men arrived at the hospital in personal vehicles and are being treated for injuries, per the AP.