In 2000, 10 people were shot, seven fatally, in a Philadelphia crack house. Four men were convicted in connection with the crime.
In 2014, Bradley William Stone killed his ex-wife and five of her family members in Montgomery County before committing suicide.
In 2006, Charles Carl Roberts killed five girls at an Amish schoolhouse in Lancaster County before killing himself.
In 1934, five people died when gunmen opened fire on a parade in Schuylkill County. Six people were convicted in connection with the massacre, but none confessed and no motive was ever officially established.