At least six people have been killed and one wounded in three locations in Pennsylvania, near Philadelphia, said U.S. officials.
The suspect Bradley William Stone aged 35 has killed his ex-wife Nicole Stone, her mother, her grandmother, her sister, her sister's husband and 14- year old daughter.
Police is seeking the suspected gunman who killed the six people over alleged custody dispute, reported the BBC.
The first shooting took place at Stone's former sister in-law's house in Souderton where she was killed along with her husband, Aaron Flick and the couple's daughter while their son was extremely wounded.
The next shooting was at a house near Lansdale where Nicole Stone's mother, Joanne Hill, and grandmother Patricia Hill were killed.
Nicole Stone was later killed at her home in Harleysville where her neighbours saw Stone run away with their two children. The children were later found safe a short distance away.