A six-ship flotilla carrying more than 600 pro-Palestinian activists and 10,000 tons of supplies is heading for the Gaza Strip as the Israeli navy prepares to intercept it.
Three Israeli naval missile boats left their base in Haifa late Sunday to prevent the ships from entering a 32-kilometer exclusion zone enforced by Israel along Gaza's Mediterranean Sea coast.
Turkish NTV, a private television station, reported early Monday that eyewitness say Israeli helicopter gunships fired on one of the vessels in international waters, killing two and wounding 30. The report has not been confirmed, and Israel has yet to comment on the report.
Earlier, an Israeli official said the navy warned the convoy by radio not to approach Gaza, told the captains of the boats they were approaching a blockaded area and asked them to either proceed to the Israeli port of Ashdod or turn back.
Activists on board responded that they would continue toward their destination. The al-Jazeera satellite channel reported the flotilla changed course and slowed down in an attempt to avoid a nighttime confrontation.
Israeli authorities say that while they want to minimize violence, the navy will intercept the ships once they enter Israel's territorial waters.
The flotilla will then be towed to Ashdod, where the foreign nationals aboard will be brought to a detention center and given a choice of deportation or jail if they refuse to be deported voluntarily.
Israeli government spokesman Yigal Palmor says aid supplies will be confiscated and examined before possibly being transferred to Gaza.
Organizers from the Free Gaza Movement and a Turkish human rights group say the convoy, which includes three cargo ships and three passenger boats, is carrying medical supplies as well as cement and other building materials.
They say the construction supplies are intended to help Gazans rebuild homes destroyed during Israel's military offensive in the Islamist-controlled territory early last year.
Flotilla organizer Greta Berlin says its aim is to break Israel's three-year blockade of Gaza, which was instituted after the Palestinian militant group Hamas seized control of the territory in 2007.
Israel says it has banned construction materials, including concrete and steel, from entering Gaza due to security concerns. U.N. officials and international aid groups say the blockade has devastated the local economy and failed to weaken Hamas's grip on power.
Activists have rejected an Israeli offer to unload their humanitarian aid at a port in Israel, for transfer to Gaza via international organizations.
The protesters on board the ships, including human-rights workers and lawmakers from several European countries, say they hope to broadcast any confrontation with Israeli forces live on television and via the Internet.
They say two additional ships could follow later this week.
The ships, which departed Mediterranean ports in Europe and Turkey over the past week, set sail for Gaza Sunday from international waters off the coast of Cyprus after two days of delays.
Some information for this report provided by AP, AFP and Reuters.