GAZA CITY, Gaza Strip -- An Israeli missile ripped through a two-story home in a residential area of Gaza City Sunday, killing at least 11 civilians, including four young children and an 81-year-old woman, in the single deadliest attack of Israel's offensive against Islamic militants.
The bloodshed was likely to raise pressure on Israel to end the fighting, even as it pledged to intensify the offensive by striking the homes of wanted militants. High numbers of civilian casualties in an offensive four years ago led to fierce criticism and condemnation of Israel.
In all, 73 Palestinians, including 37 civilians, have been killed in the five-day onslaught. Three Israeli civilians have also died from Palestinian rocket fire.
President Barack Obama said during a visit in Thailand that he was in touch with players across the region in hopes of halting the fighting, while also warning of the risks of Israel expanding its air assault into a ground war. "We're going to have to see what kind of progress we can make in the next 24, 36, 48 hours," he said.
Obama blamed Palestinian militants for starting the round of fighting by raining rockets onto Israel and said the United States supported Israel's right to protect itself. "Israel has every right to expect that it does not have missiles fired into its territory," Obama said.
On the ground, there were no signs of any letup in the fighting as Israel announced it was widening the offensive to target the military commanders of the ruling Hamas group.
The Israeli military carried out dozens of airstrikes throughout the day, and naval forces bombarded targets along Gaza's Mediterranean coast. Many of the attacks focused on homes where militant leaders or weapons were believed to be hidden.
Palestinian militants continued to barrage Israel with rockets, firing more than 100 Sunday, and setting off air raid sirens across the southern part of the country. Some 40 rockets were intercepted by Israel's U.S.-financed "Iron Dome" rocket-defense system, including two that targeted the metropolis of Tel Aviv. At least 10 Israelis were wounded by shrapnel.
Israel's decision to step up its attacks in Gaza marked a new and risky phase of the operation, given the likelihood of civilian casualties in the densely populated territory of 1.6 million Palestinians. Israel launched the offensive Wednesday in what it said was an effort to end months of intensifying rocket fire from the Hamas-ruled Gaza Strip.
Israel placed the blame on militants, saying they were intentionally operating in places inhabited by civilians. The military has released videos and images of what it says are militants firing rockets from mosques, schools and public buildings.
"Hamas is using the Gaza population as human shields," said Brig. Gen. Yoav Mordechai, the chief Israeli spokesman. "They are exploiting crowded residential urban areas."