Palestinian militant groups in the Gaza Strip on Sunday said they shot down an Israeli Apache helicopter, an Al Arabiya correspondent reported, adding that a long range missile was also intercepted over Tel Aviv.
The official Turkish news agency, Anatolia, meanwhile, reported that Izz el-Deen Al-Qassam Brigades, Hamas' armed wing, hit an Israeli warship off the coast of Gaza with three "107M" missiles.
An Al Arabiya correspondent in the coastal enclave also reported that explosions were heard in Eilat in southern Israel.
Meanwhile, at least 11 Palestinian civilians, including four children, were killed on Sunday in what Hamas said was an Israeli air strike on a Gaza apartment building, the highest death toll in a single incident in five days of fighting.
Israel gave off signs of a possible ground invasion of the Hamas-run enclave as the next stage in its air and sea offensive billed as a bid to stop Palestinian rocket fire into the Jewish state, while also spelling out its conditions for a truce.
A spokesman for the Hamas-run Interior Ministry said an Israeli missile wrecked the three-story residential building, killing 11 people, all of them civilians. Medics said four women and four children were among the dead.
The Israeli military had no immediate comment. Prime Minister Benjamin Netanyahu said earlier that he had assured world leaders that Israel was doing its utmost to avoid causing civilian casualties in the military showdown with Hamas.
"The massacre of the Dalu family will not pass without punishment," Hamas's armed wing said in a statement.
For their part, Gaza militants launched dozens of rockets into Israel and targeted its commercial capital, Tel Aviv, for a fourth day. The Jewish state's "Iron Dome" missile shield shot down two of the rockets fired toward Tel Aviv, Israel's biggest city, but falling debris from the interception hit a car, which caught fire. Its driver was not hurt.
In scenes recalling Israel's 2008-2009 winter incursion into Gaza, tanks, artillery and infantry massed in field encampments along the sandy, fenced-off border. Military convoys moved on roads in the area newly closed to civilian traffic.
Netanyahu said Israel was ready to widen its offensive.
"We are exacting a heavy price from Hamas and the terrorist organizations and the Israel Defence Forces are prepared for a significant expansion of the operation," he said at a cabinet meeting, giving no further details.
Gaza health official Mufid al-Miklalati said 65 Palestinians - around half of them women and children - have been killed in small, densely populated Gaza began, with hundreds wounded.
More than 500 rockets fired from Gaza have hit Israel since Wednesday, killing three civilians and wounding dozens.
Israel's declared goal is to deplete Gaza arsenals and force the Islamist Hamas to stop rocket fire that has bedeviled Israeli border towns for years and is now displaying greater range, putting Tel Aviv and Jerusalem in the crosshairs.
Israel withdrew settlers from Gaza in 2005 and two years later Hamas took control of the impoverished enclave, which the Israelis have kept under blockade.