A suspected leak was detected overnight in an undersea gas pipeline connecting the Finnish and Estonian grids.

Just before 2 a.m. local time on Sunday, the Finnish and Estonian gas transmission system operators noticed “an unusual drop in pressure in the offshore gas pipeline between the two countries,” Gasgrid Finland Oy said in a statement on its website.

While the current incident appears contained for now, the potential risks will be reminiscent of blasts on the undersea Nord Stream gas pipeline just over a year ago. That pipeline was ruptured in four places by what Sweden’s investigation later found to have been detonations. Authorities haven’t yet determined who was behind those explosions.

Read More: Nord Stream Mystery Brings Infrastructure Fears to Surface

The valves in the 77-kilometer (48-mile) Balticconnector offshore pipeline are now closed and the leak is stopped, Gasgrid Finland said, adding that it’s currently investigating the matter in cooperation with Estonia’s Elering AS.

Finland’s gas system is stable and supply is secured through the Inkoo floating LNG terminal, it said. Estonian users are supplied from Latvia, Elering said in a separate statement.

--With assistance from Ott Tammik.