COPENHAGEN, Denmark (AP) — Danish officials on Tuesday confirmed that there has been “extensive damage” to the Nord Stream 1 and 2 gas pipelines in the Baltic Sea off Denmark and that the cause of the damage was “powerful explosions.”

In a statement, the Copenhagen Police said it had carried out a number of preliminary investigations of what it called “the crime scenes," with assistance from Denmark's Armed Forces and in collaboration with, among others, the Danish security and intelligence agency.

The agency and the police have decided to set up a joint investigation group which will handle the further investigation of the incidents, the police said, adding it was “not possible to say when the investigation can be expected to be completed.”

Earlier this month, the Swedish domestic security agency said its preliminary investigation of two further leaks closer to its coast “has strengthened the suspicions of serious sabotage” and a prosecutor said evidence at the site has been seized.

Swedish newspaper Expressen published Tuesday what it claims is a video of the damaged pipelines off Sweden and said that at least 50 meters (165 feet) of the metal pipe appears to be missing

The four leaks occurred in international but within the exclusive economic zone of Denmark and Sweden. The damaged Nord Stream pipelines discharged huge amounts of methane, a potent greenhouse gas, into the air for several days.