Shaken partygoers at the New Jersey barbecue-turned-mass shooting recounted the horror to The Post on Sunday — as one said the violence stemmed from a decades-old turf war.

“I was sitting on a chair talking to my daughter and a friend. We were laughing. Next thing I knew, I hear shots fired, like 20 shots,’’ Sunshine Carter, 44, said of the deadly gunfire that broke out at a sprawling home in Fairfield Township in southern Cumberland County late Saturday.

“Then it stopped, then 10, 15 more,’’ Carter said of the bullets. “I didn’t know if they had to reload. I didn’t know if it was two shooters, one shooter. I was running for my dear life.

“A girl ran in front of me, got shot. It could have been me. My friend was trying to help her.”

Two people were killed in the carnage: 25-year-old Asia Hester, a Jamaican immigrant and hardworking health care staffer, and Kevin Elliot, 30. 

Some guests suggested that the man was the target — with the shooting stemming from two local rival factions of young men.

“It’s South Side young boys vs. North Side young boys,’’ said a female guest who asked not to be identified.

“This has been going on since the ’60s, and now they’re getting crazier with it. They’re bringing guns.

“Usually, when they do that, they let off a couple [rounds], and that’s it,’’ she said. “But last night, they just kept going. People were running, falling. People were dying. It went on for 5, 10 minutes, running from bullets.”

Carter said the female homeowner is a “family-oriented woman” who was throwing a 1990s-themed birthday bash for her nephew complete with a DJ, tents and security when shots rang out at the house across from a cemetery in the bucolic area.

The guest described how she frantically searched for her kids amid the chaos.

“They’re grown, but they’re still my kids. I’m running around looking for them, I can’t find them. I can’t find my phone to call them,’’ Carter recalled.

“I’m being trampled on. All because we had a family barbecue. We were having a good day, a good time. These idiots just come in and shoot innocent people, and for what? Why? Just crazy.

“I didn’t see anybody arguing before. It was just out of the blue — pop, pop, pop, pop, pop — and we hauled a–.

“We’ve never been through anything like this before. This is a family home,” Carter said.

“And to come when everyone’s having a good time and just start shooting? Come on now, you bastards.”

A friend of Elliott’s, who wished to remain anonymous, called his death “tragic.”

“He was a good kid who’d made his peace with life and had trouble with nobody. He showed up to a party to celebrate a happy occasion, and ended up dead. I can’t make sense of it,” the friend said. 

As mourners packed Hester’s family home less than a mile from the scene Sunday, her weeping sister, Crystal, told The Post, “I talked to her yesterday before she went [to the party].

“She didn’t deserve this,’’ the shattered sibling said.

A male relative decried the senseless bloodshed.

“She was a good person, very respectable,” he said of Hester. “It’s just a tragic situation. Something’s got to be done.’’

The dead woman’s family said she graduated from Rowan College in South Jersey and worked in health care. Her Facebook page listed her employer as Jefferson Health.

She was originally from Kingston, Jamaica, according to her page.

“She was an A student,’’ said Laquanta Davis, 26, who grew up with Hester.

“She didn’t get out much,’’ Davis said. “She wasn’t the type who went out to parties, so that took me by surprise.

“Who would have ever thought it would turn out this way for her. She was so sweet — so sweet and loving,” Davis said.