The Philadelphia shooting was one of at least five across the nation involving four or more victims in a violent 27-hour span, including one that left three people dead and 11 injured in Chattanooga, Tennessee, another in which three people were killed at a graduation party in Socorro, Texas, and yet another that left a 14-year-old girl dead and eight people injured at a strip mall in Phoenix, Arizona, according to the Gun Violence Archive, a website that tracks shootings across the nation.
In total, nine people were killed and 37 injured in the five shootings.
The Philadelphia shooting erupted just before midnight at the busy intersection of Third and South streets.
MORE: What we know about victims killed in Philadelphia mass shooting
Inspector D.F. Pace of the Philadelphia Police Department said hundreds of people were milling about the area when the shooting caused a panic and sent people running in all directions, some diving behind cars for cover.
"There were hundreds of individuals just enjoying South Street, as they do every single weekend, when the shooting broke out," Pace told reporters.
Philadelphia Police Commissioner Danielle Outlaw said at a press conference Sunday afternoon that a police officer responding to gunshots in the area witnessed a man firing a gun into a crowd and attempted to detain him. Outlaw said the officer fired at the armed man three times before losing the assailant in the crowd.
Outlaw said investigators believe the officer shot the gunman, who is still being sought.
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No arrests have been announced. Investigators are combing through security video in hopes of identifying the suspects and determining a motive for the shooting.
Outlaw said the shooting possibly started during a physical confrontation between two people, including one of the people killed in the incident.
"These individuals eventually began firing at one another with both being struck, one fatally," Outlaw said.
The names of the three people killed in the episode -- a 34-year-old man, a 27-year-old woman and a 22-year-old man -- were not immediately released. Outlaw said two of the slain victims were innocent bystanders as well as many of those who were wounded.
One of those killed was identified as Kris Minners, a resident adviser at Girard College in Philadelphia, the Girard College Federation of Teachers union said in a statement. Two more victims were identified by the Philadelphia Police Department Sunday afternoon as 34-year-old Gregory Jackson and 27-year-old Alexis Quinn.
"The loss of Kris reminds us that gun violence can and will touch everyone in our nation as long as our elected officials allow it to continue," the teachers' union statement read.
Police recovered two guns from the scene, including one with an extended magazine, authorities said. Shell casings from at least five different caliber guns were collected at the scene, authorities said.
MORE: Will Congress act on guns after string of mass shootings?
Seven of the wounded victims were taken to Thomas Jefferson University Hospital, overwhelming the emergency room staff and prompting 911 dispatchers to direct first responders to take additional victims to two other area hospitals.
Outlaw said the injured victims are 17 to 69 years old and their conditions ranged from stable to critical.
"This is beyond unacceptable," said Outlaw, who asked any witnesses of the shooting to contact police.
The mass shooting came on the heels of a deadly Memorial Day weekend in Philadelphia, in which more than 40 people were shot in separate incidents across the city, including a 9-year-old boy and his father returning to their home from a holiday cookout, police said.
As of midnight Saturday, Philadelphia had recorded 211 homicides this year, 14 fewer than this time in 2021, a year that saw a record 562 homicides, according to Philadelphia Police Department crime statistics.
2nd mass shooting in Chattanooga in the last week
Chattanooga, Tennessee, police are investigating the city's second mass shooting for the second weekend in a row after a barrage of shots from multiple gunmen early Sunday left three people dead and 11 injured, officials said.
The shooting occurred around 3 a.m. outside a bar downtown Chattanooga.
Chattanooga police Chief Celeste Murphy said multiple gunmen are suspected in the shooting. She said of the three people killed, two were shot to death and one was struck by a car fleeing the scene.
No arrests have been announced.
The incident follows a mass shooting that occurred in downtown Chattanooga on May 28 in which six teenagers were shot, including two who were critically injured.
14-year-old shot dead in Phoenix
The Phoenix shooting broke out around 1 a.m. local time Saturday at a strip mall in the northern part of the city where more than 100 people were attending a party, according to the Phoenix Police Department. A 14-year-old girl was fatally shot in the incident, two women suffered life-threatening injuries and another six victims, including a teenager, sustained non-life-threatening injuries, police said.
"I heard over a hundred gunshots going off," a woman who witnessed the shooting told ABC affiliate station KNXV-TV in Phoenix.
She said that prior to the shooting, she heard cars doing burnouts and donuts in the street. Once the gunfire erupted, the witness said she saw people screaming and running in all directions.
"I, myself, was like hiding behind cars as the shots kept getting closer and closer," the witness said.
Phoenix Mayor Kate Gallego took to Twitter to voice her frustration over the surge in gun violence in her city and across the country, writing, "Seems we can't go a day without another mass shooting."
"Time has run out," Gallego tweeted. "Change must happen now."
Seems we can’t go a day without another mass shooting.— Mayor Kate Gallego (@MayorGallego) June 4, 2022
This time, it’s Phoenix, at 10th Ave & Hatcher.
Time has run out.
Change must happen now.
4 shot, 2 fatally, in Mesa, Arizona
Two men were killed and two people were wounded in a shooting that occurred early Sunday outside a bar in Mesa, Arizona.
Sgt. Chuck Trapani of the Mesa Police Department said the shooting occurred around 2:30 a.m. outside The Lounge Soho. He said police went to the scene to investigate a report of gunshots and found two men shot in the parking lot. The victims were pronounced dead at the scene.
Trapani said officers searched the area and found two more wounded people, who were taken to area hospitals.
Trapani told KNXV that officers arriving on the scene saw a silver car speeding away and chased it. Police stopped the car and detained three occupants.
He said that while no guns were found in the car, a weapon was found along the path the vehicle fled.
5 teens shot at graduation party
Five teenagers were shot and wounded Saturday night at a graduation party in Socorro, Texas, a suburb of El Paso, according to police.
No arrests have been announced.
Socorro Police Chief David Burton said at a news conference that two teenagers were in critical condition.
Burton said that about 100 teenagers and young adults were attending a graduation party at a home when an individual began firing into the crowd.
He said the wounded victims ranged in age from 16 to 18.
Burton said different caliber shell casings were found at the scene, but police have not confirmed whether more than one shooter was involved.
"The initial investigation indicates this was a targeted attack," Burton said. "There is no immediate threat to the public."
No arrests have been announced.
The mass shootings followed President Joe Biden's prime-time speech Thursday addressing the surge in gun violence across the nation, including the rampage at a Uvalde, Texas, elementary school on May 24 that left 19 students and two teachers dead, a racially-motivated massacre at a Buffalo, New York, supermarket that left 10 dead and three wounded, and a shooting Wednesday at a medical office in Tulsa, Oklahoma that in which a doctor and three other people were fatally shot.
Biden called for a federal ban on assault weapons and implored Congress act, saying, "We can't fail the American people again."
Since 2017, mass shootings in the United States -- described as shooting incidents in which at least four people are injured or killed -- have nearly doubled year over year. Already, there have been 212 mass shooting incidents in 2022 -- a 50% increase from 141 shootings in May 2017. The graphic above shows the number of shooting incidents per state. Mobile users: Click here to see our map of mass shootings in the US from the last five years
The number of people injured or killed does not include the suspect or perpetrator. These graphics show the number of victims across all mass shootings from the last five years.