Armed masked men around the Greek islands have been targeting migrant boats and turning them back, sometimes throwing their engines away, according to a damning HRW report. This follows witness claims of Greek border guards refusing asylum seekers entry.

The report bases its findings on nine witness testimonies detailing cases of masked, often armed, assailants intercepting boats off the Aegean Sea coast, which are usually headed from neighboring Turkey carrying refugees from the Syrian war.

The most recent case allegedly took place on October 7 and 9, when the attackers allegedly disabled the engines of several boats and even punctured holes in their inflatable hulls. Some of the boats were towed back into Turkish waters.

There is virtually no guarantee any of the people would survive such conditions. This has prompted an outcry from Human Rights Watch, whose Greece specialist, Eva Cosse, says these “criminal actions require an urgent response from the Greek authorities.”

The allegations follow repeated cases of Greek border guards turning migrants back toward Turkey across the land border at Evros. On October 9, HRW staff saw one inflatable rubber boat drifting in neutral waters for more than an hour. The boat was loaded over capacity and looked set to perish. Thankfully, a group of volunteer Spanish lifeguards came to the rescue in their own boat.

Speaking to HRW, a 17-year-old Afghan refugee recounted how the passengers in the boat he was on had felt when they were captured by a boat containing five masked men in balaclavas carrying guns. Their rubber dinghy, filled to the brim with women and children, had set off from the Turkish shore at Assos headed for the Greek island of Lesbos.

They were intercepted 30 minutes into their journey. “At first when they approached, we thought they had come to help us,” Ali told HRW. “But by the way they acted, we realized they hadn’t come to help. They were so aggressive. They didn’t come on board our boat, but they took our boat’s engine and then sped away.”

According to Ali, the men attacked three more boats before heading back toward the Greek coast.

Three similar incidents involving masked men have been described to HRW by more than one witness. In some cases, HRW was told that a Greek flag had been visible on the intercepting boats.

CBS has obtained video footage depicting one such encounter, where destitute and downtrodden refugees were simply left to die in open water with no engine.