A crazed son fatally stabbed his parents inside the Italian deli the couple owned on Long Island Thursday morning, according to sources and locals who frequented the shop.

The 30-year-old suspect allegedly knifed his mom, 62, and dad, 70, just after 9 a.m. inside the A & A Italian Deli on Hicksville Road near Boundary Avenue in Bethpage, cops and sources said.

He was taken into custody. His name was not released by cops.

A family friend, who asked not to be identified, said the couple’s son had been battling a hard drug addiction for years and has been in trouble with the law before.

She described the couple — who were not immediately publicly identified by authorities — as loving, warm-hearted and kind people who would often go out of their way to make others feel welcomed.

“They were just great people,” the family friend said.

“When I lost someone close to me, [she] just showed up to my house with a tray of ziti and stayed with me for over two hours,” she said about the mother.

“That’s the kind of people they were.”

A deli customer who only identified himself as George said the slain couple “seemed like great people,” and that he’d often chat with them while waiting for his food.

“Very friendly people and they had great prices — It’s very sad,” he told The Post. “It’s such a shame. They had great sandwiches.”

Another frequent visitor said she was shocked to learn about the slaying, and recalled the couple has a son who was “off.”

The investigation was ongoing, cops said.