Israeli naval forces intercepted the Global Sumud Flotilla — more than 40 boats carrying about 500 activists and symbolic humanitarian aid bound for Gaza — in a large-scale overnight operation that ended Thursday morning.

Dozens of activists, including Greta Thunberg, former Barcelona mayor Ada Colau, and European Parliament member Rima Hassan, were detained and will be deported.

Organizers said contact was lost with most of the flotilla, though a few vessels briefly remained at sea before being boarded near Gaza’s coast, the Associated Press has reported.

The interception, carried out in international waters, was mostly peaceful but drew widespread international condemnation and sparked protests in cities including Rome, Istanbul, Athens, and Buenos Aires.

Italy’s largest union has called a one-day general strike in response.