FHP says one of the drivers was trying to pass traffic and hit another vehicle, head-on.

The crew members were in a "confined space" on board a moored barge when their coworkers lost contact with them, the Coast Guard said.

The incident occurred at Zablan Beach Park in Oahu on Monday, March 16 — and officials tell PEOPLE it "wouldn't have happened on a regular day" ...

Crews are working to stabilize the hill and, below at Waimea Bay, lifeguards are making sure no one gets too close to it.

Two crew members of a tugboat were killed and two others were injured in what the Coast Guard described as a “confined space incident” aboard a barge moored in southeast Alaska.