A man went on a stabbing rampage along a Philadelphia street, randomly attacking a people at a cellphone store and inside a car and killing a man at a mechanic shop, police said.

The death was one of six killings on a violent Tuesday in the city.

The violence began in the afternoon when police say a 55-year-old man entered a Cricket Wireless store and stabbed a man in the chest who was paying his bill. The man then fled and climbed into a car and stabbed the driver in each hand. Police say the man, who hasn't been identified, headed to a nearby mechanic and stabbed a 30-year-old man in the chest who was watching repairs on his car. Police say that man collapsed in the road and later died from his injuries.

The two other victims drove themselves to a hospital and were in stable condition. The suspect was taken into custody, still holding the knife, but has not been charged.

"They're clearly unprovoked attacks at this point," Philadelphia Police Lieutenant John Walker told WCAU-TV. "We're not sure what the motivation is behind this male."

A few hours later, investigators say gunfire broke out in another part of the city, leaving one man dead and another in critical condition.

Over the next several hours, police say four more men were killed in four separate shootings.

No arrests have been made in any of the shootings.

All of the killings happened in different neighborhoods, and police aren't saying whether any of them are connected.