JERUSALEM (JTA) — Israel’s Navy stopped a boat carrying 17 Palestinians from Gaza that attempted to breach the maritime blockade of the coastal strip.

The boat was stopped late Tuesday afternoon and towed to the southern Israeli port of Ashdod, according to the Israel Defense Forces. The Navy fired warning shots when the boat crossed the blockade line, according to Haaretz.

The attempt to leave Gaza by sea, which comes amid a barrage of mortars and rockets being fired at southern Israel on Tuesday from Gaza, is being called a “reverse flotilla” because it is the first public attempt to break out of the blockade and not into it.

The boat carried activists, students and patients in need of medical treatment outside the Gaza Strip. Israel said it would provide medical assistance to the sick and disabled passengers. The passengers will be returned to the Gaza Strip, however, according to the IDF.

“The Hamas terror organization, who is responsible for this attempt to breach the naval blockade, is trying to carry out a propaganda operation while using its people,” the IDF spokesman said in a tweet.

In a statement, the IDF said “The naval blockade is a necessary and legal security measure that’s been repeatedly recognized by the world and the UN as important to the security of the State of Israel and its maritime borders that protect Israeli civilians in the face of terror. The IDF will continue to enforce the naval blockade and defend the maritime borders of Israel and its civilians.”

Israel and Egypt launched the joint blockade of the Gaza coast in 2007 after Hamas took control of the strip.

U.S. Middle East peace envoy Jason Greenblatt said in a tweet Tuesday that the flotilla could harm Palestinian civilians.

“Shame on all involved in inciting the so called “reverse flotilla” today. Hamas treats this like a play being acted out for a live media audience. But these are real lives Hamas is cynically risking in a grim bid to hold on to power,” he tweeted.

Greenblatt added: “There is no shortcut for a better future for all people in the region. Hamas must stop with deadly theatrics needlessly putting lives at risk and begin the process of building better lives for the Palestinians of Gaza and their neighbors.”

The attempt comes days before the eighth anniversary of the Mavi Marmara incident, when Israeli commandos killed nine Turkish citizens in clashes on a boat that sailed with five others from Cyprus in an attempt to break the Gaza blockade.