A mass shooting in Philadelphia's Grays Ferry neighborhood left three people dead and 10 others injured early Monday morning, police say.

Philadelphia Police Commissioner Kevin Bethel said the shooting occurred on the 1500 block of South 27th Street just before 1 a.m.

Police said nine victims were taken to Penn Presbyterian Medical Center and three others were taken to Children's Hospital of Philadelphia. One additional victim walked into the Hospital of the University of Pennsylvania's Pavilion Campus. Bethel said at least eight of the victims were transported by police.

Bethel said among the injured shooting victims, two of them were juveniles and both are expected to survive.

Bethel said officers had already responded to the same block late Saturday night into early Sunday. Police made arrests during that earlier incident and continued to monitor the area throughout the weekend. Officers then returned Sunday after receiving reports of loud music. While responding to a separate incident nearby, officers heard gunfire and rushed back to the block.

Bethel said he believes there were around 40 individuals who may have been present at the time of the shooting. He added there may have been an exchange of gunfire and dozens of shell casings were recovered from the scene.

Police said one person was taken into custody with a weapon, though their role in the shooting is unclear.

Officers had been monitoring the block earlier in the weekend after responding to prior disturbances and arrests related to loud music and gatherings. Police were dispatched to a nearby priority call when they heard gunfire on their return.

Bethel described the incident as part of a violent Fourth of July weekend in the city, which saw six homicides and numerous shootings.

Over the weekend, eight people were injured after a shooter, possibly multiple shooters, opened fire at a South Philadelphia nightclub.

Bethel says the city remains down more than 12% in homicides and 10% in shootings year-over-year. He added that the department's Homicide Unit has a 95% clearance rate, while the Shooting Investigation Group has cleared 36% of its cases.