North Slope workers along the Dalton Highway reported a small plane crash near Atigun Pass, Alaska State Troopers say.

Just after 1:45 p.m., troopers received a call from Alyeska Pipeline security personnel at Pump Station 4, near Mile 269 on the Dalton Highway, saying they had gotten word of a small plane crash near Atigun Pass.

The security team at Pump Station 4 reported a team of medical personnel heading to the site to assist four victims, all of whom survived the initial crash with injuries. All four victims were transported to a nearby airstrip to be taken to a hospital for treatment, where they were listed in critical condition.

"We don't have anyone on scene yet," said AST spokesperson Beth Ipsen. "A Wildlife Trooper from Cold Foot is being called to the area too, and the security team has medical personnel heading that way."

Investigators with the National Transportation Safety Board have also been notified, and have a team on standby in Anchorage if necessary. 

"At this point right now, details are very sketchy. We're working closely with the Alaska State Troopers and also the FAA out of Fairbanks,” said NSTB Investigator Clint Johnson. “At this point right now, we know it was a single engine airplane. Quite frankly we don't know if this is a type of flight we refer to as part 91, which is personal use, or part 135, which would be for hire. There's a little a confusion on that and we'll get to the bottom of that.”

This is a developing story, please check back for updates.