The gunman on the run after shooting a security guard for a Manhattan supportive housing nonprofit had an ongoing beef with the victim, the Daily News has learned.

Cops are still searching for the triggerman, who police believe shot the guard down the block from the Prince George on E. 28th St. in NoMad just a few blocks from Madison Square Park, a police source said.

“He’s a very selfless person,” the victim’s step-sister told The News Tuesday. “That was one of the jobs that he’s been doing for a long time that he loves to do.”

The 49-year-old security guard had stepped out to get lunch and was coming out of a Whole Foods down the block from his job when he was shot at about 12:30 p.m. Monday.

The gunman, one witness said, opened fire “in broad daylight in front of 70 people.”

Medics rushed the victim to Bellevue Hospital.

“He’s still in the hospital. Right now we don’t know much of his prognosis,” said the step-sister, who asked not to be named. “[Doctors] don’t have much to say. They’re just working on him.”

The Prince George on E. 28th St. in NoMad, Manhattan. (Google)
The Prince George on E. 28th St. in NoMad, Manhattan. (Google)

Police sources and residents of the Prince George said the gunman had an ongoing beef with the security guard and that the two men had argued in the days leading up to the shooting.

The victim’s step-sister said he would avoid any sort of conflict.

“He’s not the type of person who argue with people,” she said. “Even if you try to force him, he would just brush it aside. He never try to start nothing with people. If you try to start something with him, the best you get out of him is like, ‘Nah, man, it’s not necessary.’”

“He’s very friendly, very helping,” she added. “That’s his nature since he was young. That’s just how he was. He still is that way.”

The Prince George — which is listed on the National Register of Historic Places — includes 416 units of affordable housing operated by Breaking Ground, a non-for-profit that builds and operates supportive housing at locations throughout the city.

“Breaking Ground is deeply saddened by the incident involving one of our security guards,” Miranda Hall, a spokeswoman for the nonprofit organization, said in a statement Monday. “Our thoughts are with them and their loved ones, and the safety of our tenants, staff and community is our top priority.”

This story has been updated

With Sheetal Banchariya, Kerry Burke and Nicholas Williams