COPENHAGEN, Denmark (AP) – Norway’s navy says one of its frigates has almost completely gone under water after an oil tanker rammed into it last week, tearing a large hole in its side.

Rear Adm. Nils Andreas Stensoenes, the head of Norway’s navy, says several of the wires used to stabilize the KNM Helge Instad snapped Tuesday, causing the vessel to sink further into the fjord.

Only the top of the frigate with its radar and antennas remained above the waterline.

The 134-meter (442-foot) frigate began listing heavily after a Maltese-flagged oil tanker collided with it Thursday. Its 137 crew were evacuated.

The tanker was only slight damaged in the collision in Sture, north of Bergen.

Authorities are investigating the cause of the accident.