A Roxborough man was arrested in connection with two shootings that took place just a few hours after a late-night Labor Day celebration in Manayunk.

In the early morning hours of Sept. 8, two people were shot in a parking lot off the 4100 block of Main Street, in the heart of Manayunk's downtown strip. A 24-year-old woman was shot once in the calf, and a 30-year-old man was shot once in the buttocks, according to Lt. Frank Vanore, a police department spokesman.

Both victims, whose names were not released, were taken to Temple University Hospital with non-life-threatening injuries.

Investigators from Northwest Detectives collected evidence from the scene, including shell casings from 9mm handgun, Vanore said. The detectives developed a suspect after speaking with those at the scene.

"After interviewing several people, they believe the motive was an argument," Vanore said.

Arrested and charged with the shootings was Julius Walker, a 22-year-old from the 400 block of Domino Lane. Vanore said Walker, who has a criminal history, will be charged with aggravated assault, shooting and weapons offenses.

Vanore said Walker is listed as having five prior arrests, the latest a violation of criminal registration. Vanore explained the latter as being a requirement that an adult recently released from prison must inform local authorities of their residence. Not informing police of an address change within five years of being out of prison is grounds for an arrest, Vanore said.

Police don't typically go after people guilty of violating criminal registration, but if an offender is stopped for something else, he or she will usually face consequences, he said.

"He (Walker) failed to let us know he was out, and failed to provide the prints and information," required as part of the condition of his release, Vanore said.

Walker also had narcotics violations and weapons charges dating to 2004 and 2006, respectively.

"It appears he's a frequent flier," Vanore said.

Vanore confirmed that the shootings took place in the Parkway parking lot, a municipal parking area on Lock Street off of Main Street.

After combing vehicles and collecting physical evidence, Northwest Detectives were able to develop their suspect, Vanore said, and Walker was soon in handcuffs. Vanore would not say if Walker was arrested at the scene or later on.

"It appears that he was arrested that night as part of the incident and taken into custody," he said.

Vanore could not confirm reports from anonymous sources who said the shooting likely stemmed from an altercation at a private party at a nearby bar, although he did admit it appears there had been a confrontation sometime prior to the incident.

"It (the police report) does say there was some kind of argument on that Monday," he said.

Reporter Jon Campisi can be reached at 215-354-3038 or jcampisi@phillynews.com