OSHA was at the scene of last week's crane collapse in Hawthorne Monday.

The collapse happened Friday on the site of what's to become an Amazon warehouse on Saw Mill River Road.

MORE: Police: 2 injured in crane collapse at Amazon warehouse construction site in Hawthorne

 Two construction workers were seriously injured in the collapse. One sustained an injury to the head, and the other lost a portion of their lower leg.

The scene was closed Monday and work was paused as officials continued their investigation.

"There was an additional investigator on the scene today from OSHA that had traveled in from D.C.," said Mount Pleasant Police Chief Paul Oliva. 

A spokesperson for OSHA says they're trying to determine if the employers involved complied with workplace safety standards.

News 12 also spoke with NYC Ironworkers Local 40, which confirmed one of the injured workers is in the union.

They say workers on site were trying to set a piece of steel when both that piece and the rest of the crane fell.

The warehouse, with over 200,000 square feet of combined space, is set to open in the fall. Officials say they won't know if that timeline will be delayed until the investigation is complete.

Both victims are still in intensive care at Westchester County Medical Center.

There is still no word on what could have caused the crane to collapse.