A piece of equipment collapsed onto a construction worker in Brooklyn Monday morning, fatally crushing him, officials said. 

The 46-year-old man was trying to attach an extension arm to an excavator at 1 Java St., along the waterfront in Greenpoint, around 9:15 a.m. when the extension collapsed, police and Department of Buildings Commissioner Eric Ulrich said. 

The worker, who suffered severe body trauma, was pronounced dead at the construction site, the NYPD said. His name wasn’t immediately released. 

The extension arm weighed more than 2,000 pounds, Ulrich said at a news conference. The worker, the commissioner noted, was wearing “all of his protective gear” when it fell. 

“The victim’s family is being notified as we speak, and there is an ongoing investigation right now between the police department and the Department of Buildings to determine exactly what happened this morning,” he said. 

The worker had been trying to move construction materials from one side of the site to another when the extension collapsed, he added. 

The DOB will issue a stop work order at the site before conducting a “full review” of the premises, Ulrich said. The site had not received any previous violations, he said. 

The department will also review all of the other city construction sites overseen by real estate and investment group Lendlease, the contractor at the Java Street site, the commissioner said. Lendlease is in the process of building a mixed-use development there, according to the company’s website. 

In a statement provided to NY1 Monday afternoon, Tom Reller, Lendlease’s head of communications for the Americas, said the company was “saddened to confirm a fatal construction accident occurred this morning at the 1 Java St. jobsite in Brooklyn.” 

“We extend our deepest condolences to the individual’s loved ones,” Reller said. “At this time, we are in the process of investigating the incident in full coordination with appropriate authorities.”