Palestinians have launched boats from Gaza to protest Israel's blockade, a move likely to further raise tensions after mortar fire from the enclave earlier in the day and weeks of deadly unrest.
It comes as Israel carried out strikes against militant bases in the Gaza Strip after a barrage of mortar fire from the Palestinian enclave.
'Freedom Flotilla' launches
One main boat carrying around 20 people accompanied by a group of smaller ones departed from the fishermen's port in Gaza City, AFP journalists reported and organisers said.
There were conflicting statements about whether the "Freedom Flotilla" would seek to break Israel's blockade, which currently allows them to travel nine nautical miles (16 kilometres) off the coast.
Some organisers said they would only protest, while other participants said they wanted to move past the limit.
Al Jazeera reports some of the people on the boat were protesters wounded in weeks-long demonstrations along the Gaza Strip.
Alaa Al-Battah, from the flotilla's organising committee, said the sailing of the boats "is part of our efforts to peacefully resist and break the siege on Gaza".
It was not clear how Israel's military would respond and it was yet to comment on the protest.
The boat protest comes after weeks of deadly demonstrations and clashes along the Gaza-Israel border, beginning on March 30.
Israel hits militant bases
Israel carried out strikes against militant bases in the Gaza Strip on Tuesday after a barrage of mortar fire from the Palestinian enclave further boosted tensions following weeks of deadly unrest.
The earlier firing of some 28 mortar shells toward Israel caused no injuries, with most intercepted by air defence systems, but Prime Minister Benjamin Netanyahu vowed a forceful response.
One mortar shell exploded near a kindergarten building, a military spokesman said, causing damage to the structure.
It was the largest projectile barrage from Gaza targeting Israel since a 2014 war, according to Israel's Shin Bet internal security service.
"Israel takes a grave view of the attacks on it and its communities by Hamas and Islamic Jihad from the Gaza Strip," Netanyahu said.
"The IDF will respond to these attacks powerfully," he added during a conference in northern Israel, referring to the Israel Defence Forces.
Shortly after Netanyahu spoke, Israel's military began carrying out strikes in Gaza.
At least one base belonging to Hamas and four for Islamic Jihad, an allied group, were struck, Gazan security sources said. There were no immediate reports of injuries.
Israel's military said it was "currently operating in the Gaza Strip. The explosions heard are related to this activity. Details to follow."
It did not confirm whether the response was air strikes, other means such as tank or missile fire or a combination. Gazan sources spoke of air strikes.
A Hamas spokesman confirmed only that "resistance" bases were being hit.
There was no immediate claim of responsibility for the mortars, but there was speculation they were fired by Islamic Jihad in revenge for a recent incident that left three of its members dead.
Hamas, the Islamist movement that runs the Gaza Strip, said in a statement "what the resistance carried out this morning comes within the framework of the natural right to defend our people".
"The Israeli occupation bears full responsibility for any upcoming escalation."
Image
'Clear message'
Tuesday's incidents came after weeks of deadly demonstrations and clashes along the Gaza-Israel border, beginning on March 30.
The protests have called for Palestinians who fled or were expelled in the 1948 war surrounding Israel's creation to be allowed to return to their former homes now inside Israel.
They peaked on May 14, when at least 61 Palestinians were killed as tens of thousands of Gazans protested and clashes erupted on the same day of the US transfer of its embassy in Israel from Tel Aviv to Jerusalem.
Demonstrations and clashes have continued at a low level since then. At least 121 Palestinians have been killed by Israeli fire in the unrest.
Israel says its actions are necessary to defend its borders and accuses Hamas of encouraging thousands of Palestinians to break through the border and attack Israelis.
It has fought three wars with Hamas since 2008.
But Israel has faced international criticism and calls for an independent investigation over its use of live fire during the protests and clashes along the border.
No Israelis have been killed and only one soldier has been reported lightly wounded.
