A gunman wearing a bulletproof vest opened fire on the streets of Philadelphia, Pennsylvania, on Monday night - seemingly at a random - killing five people and wounding two boys in the latest outbreak of gun violence in the United States, police said.

The shootings took place over several city blocks in the southwestern neighborhood of Kingsessing. Responding officers chased the suspect as he continued to fire. He was arrested in an alley after surrendering, police said.

No connection was immediately known between the victims and the shooter.

The gunman had a bulletproof vest, an "AR-type rifle," multiple magazines, a handgun and a police scanner, said police.

Officers were flagged down at about 8.30pm. Police found some gunshot victims and as they were attending to them, they heard more gunfire.

The suspected shooter was identified as a 40-year-old man. A second person was also taken into custody who may have returned fire at the suspect, but it was unknown whether there was a connection between the two.

Police said they found dozens of shell casings across an eight block area.

Three of the dead were 20 to 59 years old, while the fourth was estimated to be between 16 and 21. Police said a fifth victim, aged 31, was found dead in his home after he was chased and shot to death. Bullet casings were found outside the home. All victims were male. The two hospitalized victims are boys - ages 2 and 13. They were in stable condition, Outlaw said.

The shooting occurred a day after gunfire erupted at a holiday weekend block party in Baltimore, Maryland, killing two people and wounding 28 - more than half of them minors.

Police work the scene of the shooting in Kingsessing, Philadelphia. AFP

Street shooting kills five