Italian Foreign Minister Antonio Tajani instructed his embassy in Tel Aviv to reiterate his request that Israel “guarantee the absolute protection of the personnel embarked on the Gaza Flotilla.”

Italian Defense Minister Guido Crosetto on Wednesday condemned the attack and said he had redirected an Italian navy ship that was in the area to offer help.

“To ensure assistance to the Italian citizens present on the Flotilla last night, I authorized the immediate intervention of the Italian Navy’s multi-purpose frigate Fasan, which was sailing north of Crete as part of Operation Mare Sicuro. The frigate is already en route to the area for possible rescue operations,” he said.

The GSF in a press release said that at least 13 explosions were heard. No casualties were reported among the more than 500 people on board the various vessels.

The Global Sumud Flotilla is the fourth and the largest maritime challenge to Israel’s Gaza blockade this year, with 20 ships and over 500 crew, including Swedish activist Greta Thunberg and Irish actor Liam Cunningham, departing from Barcelona. The crew said a previous attack on the flotilla took place on Aug. 9 in Tunisian waters.

Israeli authorities, who have been waging war in Gaza for almost two years now in retaliation for an attack by Hamas militants, have dismissed attempts to ferry aid to the coastal enclave as publicity stunts.

This article has been updated.