Pieces of what appears to be debris from a Ground Self-Defense Force helicopter that went missing on Thursday were found early Friday in the sea off Okinawa Prefecture, with a frantic search for the 10 SDF members who were aboard so far bearing no fruit.

The helicopter had taken off from a base on the prefecture’s Miyako Island, but it disappeared from radar 10 minutes later. It had corresponded with the control tower about two minutes before it disappeared, indicating that something went wrong soon after.

The Japan Coast Guard retrieved at least 10 pieces of debris, including a large window panel that had GSDF inscribed on it and two lifeboats — one of which had a serial number showing it was installed on the missing helicopter.