By CBS3 Staff

PHILADELPHIA (CBS) –Philadelphia has announced vehicle and traffic restrictions following the South Street mass shooting. Starting at 8 p.m. on Sunday, there will be no pedestrian or vehicular traffic between Front and 6th Streets from Bainbridge to Lombard Streets until 6 a.m. on Monday.

The order comes after a mass shooting on South Street that killed three people and injured 12 others.

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At a press conference on Sunday, Philadelphia police commissioner Danielle Outlaw said one of the three victims who died in the shooting was involved in a physical altercation with another man. She said they believe that altercation was potentially the genesis of the shooting. 

Outlaw said the men then began firing at each other and both were struck. The 34-year-old involved in the altercation was pronounced dead at the hospital at 12:05 a.m., but the other man was wounded. The 34-year-old was identified as Gregory Jackson by police. 

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Police believe the other two people who died and most of the people injured were not involved in the initial incident.  

The two other victims were a 24-year-old woman and a 22-year-old man. They were both pronounced dead at Jefferson Hospital just before midnight. Police identified the woman as Alexis Quinn. 

One of the men killed has been identified as Kris Minners, a second grade resident advisor of Girard College.

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For a list of gun violence resources in Philadelphia, click here.