The Freedom Flotilla Coalition (FFC) has said the Israeli military has boarded its Gaza-bound aid ship carrying Greta Thunberg and that communication with the boat has been lost.

An aid vessel launched by Greta Thunberg and other international activists headed for Gaza was boarded by Israeli forces on Sunday, mere hours after Israeli officials demanded they “turn back,” the coalition announced in a Telegram post.

The activists had set out to protest Israel’s ongoing military campaign in the Gaza Strip, which is among the deadliest and most destructive since World War II, and its restrictions on the entry of aid.