Update 7:30 a.m. Friday: The National Transportation Safety Board is joining the search in Lake Clark for a missing plane with four people on board, after debris believed to have come from the aircraft was discovered on the lake Thursday afternoon.

Clint Johnson, the NTSB's Alaska chief, said Friday that no word of remains being found overnight Thursday had reached investigators. The National Park Service said searchers in a boat out of Port Alsworth discovered "items belonging to the occupants" of the Piper PA-28 Cherokee at about 3 p.m. Thursday.

Johnson also hadn't heard any indication that anyone from the aircraft may have survived the apparent crash.

"Obviously we would hope that would be the case, but as far as the search that's going to be down to the Park Service," Johnson said. "We know the airplane is most likely in the water, so now we're in a recovery phase."

Investigator Shaun Williams has been assigned to the incident and was en route to Lake Clark, Johnson said. The NTSB is still collecting information on weather conditions in the area between 10:30 a.m. and noon Wednesday, when the plane was headed from Port Alsworth to Merrill Field in Anchorage.

"This area over the lake is known for low-lying fog, low visibility, but conditions at the time we don't know yet," Johnson said. "We do understand that right after they became missing, weather conditions were less than stellar."

Original story:

Items found floating Thursday on Lake Clark are believed to have belonged to four people who were aboard a small, Anchorage-bound airplane that went missing Wednesday after it departed Port Alsworth.

Searchers in a boat discovered the items in the water around 3 p.m. Thursday, according to a statement from the National Park Service. The statement said the items were scattered north and east of Port Alsworth, a small community on the shores of Lake Clark, inside the vast Lake Clark National Park and Preserve.

John Quinley, of the National Park Service, said Thursday evening that he did not have information on what specifically was found in the water. He said searchers had not yet located any parts of the missing plane, a Piper PA-28 Cherokee that took off from Port Alsworth around 10:30 a.m. Wednesday.

"We've found very little at this point," Quinley said.

The Park Service statement said the families of the pilot and three passengers were being notified Thursday evening. The identities of the four people aboard the plane had not yet been publicly released by Thursday evening.

"The investigation, search and planning for recovery will continue on Friday," the statement said.

Alaska Air National Guard Staff Sgt. Edward Eagerton said Thursday that the plane had a scheduled noon Wednesday landing at Anchorage's Merrill Field but never arrived. Port Alsworth is about about 165 miles southwest of Anchorage.

By Wednesday evening, a search-and-rescue effort was underway, led by the Alaska Rescue Coordination Center at Joint Base Elmendorf-Richardson in Anchorage and involving multiple aircraft. The search continued throughout Thursday. Eagerton said searchers had received no distress signals from an emergency locator beacon, which would have helped them pinpoint where the plane could be.