The search for a missing medical transport plane that went missing Thursday near Maui continues, along with efforts to supplement a resulting shortage in air medical support in Hawaii.

There is still no sign of a medical transport plane that lost radar contact at around 9:30 p.m. Thursday — or the three crew members that were occupying it.

Aircraft debris has been found in the area, but it’s not yet clear if it belongs to the missing plane, the U.S. Coast Guard reported Friday evening. A “sheen” was also observed in the search area.

As of 5 p.m., the Coast Guard has searched about 2,400 square nautical miles of ocean to find the Beechcraft King Air 90 twin-prop and its crew. This morning it announced that its Auxiliary and the Civil Air Patrol had joined the search.

The Coast Guard said that its Cutter William Hart will continue the search overnight.

The missing plane belongs to Hawaii Life Flight, which has been providing air medical transportation in Hawaii since 2010. Following Thursday’s incident, Hawaii Life Flight grounded seven other aircraft and placed crews in a “safety stand down.”

Global Medical Response, which operates Hawaii Life Flight, said in a news release today that the safety stand down, or a pause in operations, is protocol after an accident. It’s done “so precautionary maintenance checks can be performed on all similar aircraft and so that all crewmembers can focus on their mental well-being during this difficult time,” the news release said.

The stand down has resulted in a shortage of air medical transportation between the islands, and it prompted Hawaii Gov. Josh Green to issue an emergency proclamation on Friday to shore up medical staff and aircraft to continue air medical transportation services.

Out-of-state medical personnel and a jet were summoned to aid in transportation services and were scheduled to arrive in Hawaii this morning. Two U.S. National Guard Black Hawk helicopters and a GMR helicopter, all already in Hawaii, have also been made available.

The National Transportation Safety Board said it is investigating the incident.