Palestinian resistance faction Hamas on Friday accused Israel of intentionally targeting children during its ongoing military onslaught on the blockaded Gaza Strip, now in its second week.

"[Israeli Prime Minister Benjamin] Netanyahu is murdering Gaza's children," Hamas spokesman Sami Abu Zuhri asserted in a statement.

He pledged that the Israeli premier would pay a "heavy price" for killing Palestinian children in the embattled coastal territory.

Earlier Friday, three Palestinian children were killed when their residential building in the northern Gaza Strip was struck by Israeli artillery fire.

Since July 7, when Israel's offensive against the strip began, at least 264 Palestinians-mostly civilians-have been killed in relentless air, naval and ground attacks.

Fifty-eight children and 28 women have been among those slain.

On Thursday night, the Israeli army began ground operations, sending troops into the Palestinian territory.

In recent days, thousands of Israeli troops had been called up and amassed on the strip's borders in advance of an anticipated ground assault.

Israel's ongoing offensive, dubbed "Operation Protective Edge," is the self-proclaimed Jewish state's third major assault on the embattled Gaza Strip-home to some 1.8 million Palestinians-in the last six years.