The mother of a 20-year-old man in custody for allegedly shooting a Brooklyn McDonald’s employee in a spat over cold french fries blames the employee for the shooting and said the entire staff laughed when she asked for hot fries.

Lisa Fulmore, 40, told the New York Post she spoke with her son, who said he did what he had to do.

“My son is just saying that he gotta do what he gotta do and the [victim] came after him and whatever happened, happened,’’ she said.

Fulmore said she ordered food on the McDonald’s app Monday night and was upset that her fries were cold, saying that rather than get her hot fries, an employee just put a few fresh fries on top and gave her the bag.

When she complained again, the employees started laughing. When she demanded to see the manager, they said the boss had stepped out and again laughed.

“This is when I was on the phone with my son. I was like, ‘They in this McDonald’s playing with me.’ I was like, I got kids their age, I’m not going to sit here and keep arguing with these little kids,” Fulmore said.

“He was like, ‘I’m coming down the block.’ I was like, ‘Alright.’ … Then I told him, ‘No, don’t come to McDonald’s because I don’t want you to get in trouble,’” she said.

Her son — who police said has 13 prior arrests, according to the New York Daily News — came anyway and told the staff to “back off my mother” and challenged 23-year-old man he is accused of shooting to “come outside,” the Post said.

Fulmore said the employee didn’t go outside, and she told her son to leave. About 15 or 20 minute later, she said, the male employee came out demanding to know where her son was. She said she told him he left, but the employee went outside. Ten minutes later, there was a gunshot.

“I looked, and I seen a boy on the ground, and then I saw my son running the other way. I called 911, and then I sat there and waited,” she said. Asked if her son had a gun, Fulmore said she didn’t know and “don’t even know if my son” shot the employee.

Fulmore said that the employee had “something under the blue shirt” he was wearing when he was shot. Police sources said the victim had no criminal record and there was no evidence he was carrying a weapon.

Fulmore, however, said, “There was no reason for him to go outside looking for somebody. Whatever happened outside, you caused that to happen.”

Other sources, however, told WPIX an entirely different story. They said that the son had a gun in his waistband when he arrived at the restaurant, went behind the counter and smashed property before getting into a shoving match with an employee and refusing to leave.

Fulmore, the sources said, had gone outside the restaurant. The employee who had the initial confrontation with her over the fries went outside — while the son was still inside — and encountered Fulmore. He got into another argument with her over her son’s conduct.

While they were still arguing, sources said, the son came outside and allegedly got into a fistfight with the employee. Just as the employee was gaining the upper hand in the fight, the son reportedly pulled out his gun and fired.

Sources on Tuesday said the victim was in extremely critical condition, fighting for his life, the Post said. Coworkers, friends, and family waited outside the emergency room Tuesday afternoon.

“He is a good guy,’’ a coworker told The Post.

Police said Tuesday that charges against Fulmore’s son were pending, the Daily News said.

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[Featured image: WABC screenshot]