Israel has enforced a strict naval blockade of Gaza, saying it is essential to stop weapons smuggling by Hamas, the Islamic militant group controlling the territory.

There are frequent clashes along the Israel-Gaza border, where militants from various groups try to lay bombs and fire rockets into southern Israel. Israel has also accused Hamas of building a series of tunnels close to the border, designed to facilitate infiltrations. But infiltration attempts by sea have been rare.

Monday’s shootings came amid heightened tensions after the Israeli commando raid at sea, which turned violent and left nine activists dead. The events aboard the Turkish ship, the Mavi Marmara, caused a crisis in Israel’s relations with its once close ally, Turkey, and spread concern far beyond the region, prompting calls for an international inquiry and a lifting of the blockade.

Vice President Joseph R. Biden Jr. said on Monday that the United States was “consulting closely with Egypt, as well as our other partners, on new ways to address the humanitarian, economic, security and political aspects of the situation in Gaza,” according to news reports. He issued the statement after meeting President Hosni Mubarak of Egypt in the Red Sea resort of Sharm el Sheik.

Egypt and Israel have enforced the land and sea blockade of Gaza since Hamas took full control there in 2007.

Responding to public outrage over the Israeli raid, Egypt opened its border crossing with Gaza, at Rafah, allowing passengers to flow through until further notice. Any goods coming to Gaza from Egypt still have to pass through an Israeli-controlled land crossing at Kerem Shalom.

Image Palestinians inspected the boat of four Palestinian militants who were killed by Israeli forces off the central Gaza strip on Monday. Credit... Mohammed Saber/European Pressphoto Agency

On Sunday, the French foreign minister, Bernard Kouchner, suggested a European Union role in checking cargo on board ships heading to Gaza in return for the lifting of the blockade.