Police were hunting for a gunman Monday suspected of killing six people and seriously wounding another in a series of shootings near the northeastern US city of Philadelphia.

All seven victims have a "familial relationship" to the suspect, identified as 35-year-old Bradley William Stone, said prosecutors in Montgomery County, Pennsylvania.

Police said Stone -- who uses a cane or a walker and was possibly wearing military fatigues -- should be considered "armed and dangerous" and told people to stay in their homes.

A photo of Stone which shows him with closely cropped red hair, beard and mustache was released to the public.

No possible motive was given for the shootings.

One of the dead is believed to be Stone's ex-wife, identified by local media as Nicole Hill.

Hill was believed to have been shot dead in her apartment in Lower Salford in the middle of the night in front of her two young daughters. The couple was apparently locked in a custody battle.

Hill's grandmother is believed to be one of two victims found in a home in Lansdale.

ABC television affiliate WPVI said the suspect was believed to be a military veteran.

Police stormed a home in Souderton, apparently belonging to Hill's sister. Other victims were found there, along with a teenager who was wounded and taken to hospital in a helicopter, the local NBC affiliate NBC 10 reported.

Police were searching in a fourth location, the town of Pennsburg, where Stone is a resident, prosecutors said. Residents were advised not to leave their homes.

Reinforcements were rushed in to aid the manhunt.