NORTH BERGEN, N.J. (CBSNewYork) — A birthday party turned deadly after bullets started flying early Sunday morning.

Police are investigating the shooting, which left one man dead, and multiple others are injured, CBS2’s Dave Carlin reported.

Three bullet holes are in the living room window of a home at 2033 46th St. in North Bergen, after a man invaded a family party.

Witnesses said the gunman entered and shot four people, killing one man, whose name was withheld by police while they notified his next of kin.

One person was killed and three others were wounded during a shooting at a North Bergen, New Jersey house party on May 5, 2019. (Photo: CBS2)

The longtime homeowners were injured.

Family members told Carlin the owner was shot in the side and his wife was shot in the arm because she was trying to shield her husband from bullets.

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Also wounded and expected to survive was another friend of the family.

After hearing the shots at around 4 a.m., neighbors said they watched as the injured were brought out of the home.

“There was an ambulance there, an ambulance there and one up here,” Walter Gettmann, explaining where paramedics responded.

“We saw a gentleman going in. He was about maybe 40 to 45,” another neighbor said.

Friends of the homeowners who did not want to be shown on camera told CBS2 the motive for the fatal shooting may have been the gunman wanting to confront an estranged girlfriend who was attending the party. He apparently started shooting after being told he could not go to the back of the home to see her.

Police would not confirm that.

Detectives were seen searching several blocks in the area, possibly for a weapon, Carlin reported.

Neighbors said the home is on a very quiet street and there are friendly gatherings in the residence from time to time, but nothing rowdy.

“I never hear anything, you know. If it’s a summer party, a little noise, but that’s normal. That’s it,” Luis Soliz said.

North Bergen Mayor Nicholas Sacco put out the following statement:

“This is a shocking and very disturbing incident that is in no way reflective of our North Bergen community, which is among the safest in the country according to independent studies. But as long as guns are so easily available, senseless acts of violence like this will unfortunately continue to occur,” Sacco said. “Our hearts go out to the victims and we are confident that the North Bergen Police Department and the Hudson County Prosecutor’s Office will quickly bring all those responsible to justice.”