Shootings in three communities outside Philadelphia have left at least four people dead.

A law enforcement official with knowledge of the investigation told CNN the incidents appeared to be related to a domestic dispute. The Philadelphia Inquirer, meanwhile, put the death toll at five.

A gunman shot and killed his former wife on Monday morning before moving on to a different location, where he attacked other members of his family, the unnamed official told CNN. He originally spoke of five fatalities but later adjusted that number to four.

The suspect, meanwhile, is barricaded at a home in Souderton, a borough in Montgomery County, the official added.

The attacks occurred at a number of locations within the county, said John Corcoran, deputy director of public safety. The Philadelphia Inquirer listed the communities as Lansdale, Lower Salford and Souderton.

The first shots were fired just before 4 a.m. in Lower Salford Township, Philadelphia ABC affiliate WPVI reported. Reporters from the channel observed two bullet holes in the wall at the Pheasant Run Apartments in the community of 15,000.

Police told WPVI that the suspect took two children from the apartment, both of whom were later recovered safely a short distance away. They received a call about a second shooting at 4:25 a.m and reported to another location, where they found two more people shot and killed.

A neighbor at the Lower Salford Township apartment complex told WPVI that he heard three or four gunshots.

"I heard the kids saying, 'Mommy, no! Mommy no!'" the unnamed resident told the channel.

The Philadelphia Inquirer described the current scene in Souderton as a barricade situation, and television news helicopters over the area showed SWAT crews canvassing the neighborhood.

Souderton schools had been in shelter-in-place mode but the precaution has since been lifted. Facilities in the Pennridge School District were placed on a "modified lockdown," the Philadelphia Inquirer said.

WPVI sources claimed that all victims were shot close range and that the suspect is a male military veteran. His identity is yet to be released.