ANCHORAGE, Alaska (AP) - Alaska State Troopers say two people may have been on board a small airplane spotted early Friday morning on mudflats of Knik Arm.

Neither a pilot nor a passenger was spotted near the airplane found at 6:10 a.m. about two miles northeast of the Birchwood Airport near Anchorage's north border

The Piper PA-18 Supercub, which holds two people, on Friday afternoon was under water.

Troopers spokeswoman Megan Peters says a trooper helicopter joined the Alaska Air National Guard, the Coast Guard and the Civil Air Patrol in the search for people who flew in the plane.

Troopers in Palmer took a call just after midnight reporting a downed airplane.

Troopers say the downed airplane may have left from the McGrath area.

No flights have been reported as overdue.