 Police in Philadelphia are investigating what sparked a mass shooting at a weekend party that left three people dead. On what details are known, here's correspondent Bob Brown. At least three people are dead and six wounded after shots rang out at a party in West Philadelphia. Police responding to a mass shooting around 2 a.m. Sunday morning to reports of a person with a gun. They say more than 100 people gathered for the party on the 1200 block of North Alden Street.