Details added (first version posted at 18:08)
Israel and Hamas have agreed to a truce after the worst round of violence in more than two years, a senior official from the Islamist movement ruling the Gaza Strip said Sunday.
The truce was the result of international efforts mediated by the United Nations Special Coordinator to the Middle East, Robert Serry, and Egypt, Salah al-Bardawil told the German Press Agency dpa.
Israel did not officially confirm or deny that a deal had been reached, with a prime minister's spokesman saying the government would not comment.
However, Defence Minister Ehud Barak had previously said that "if they stop firing at the (southern Israeli) communities, we will stop firing."
Calm indeed appeared to prevail on Sunday, after three days in which Palestinian militants fired rockets and mortar shells at southern Israel, sending residents to shelters. Hamas has claimed credit for half of them.
In heavy retaliatory strikes, Israel killed 19 Palestinians and injured 66 others, Gaza health services spokesman Adham Abu Selmeya said.
Abu Selmeya said about one-third of the Palestinian casualties were civilians.
They included a 41-year-old woman and her 19-year-old daughter, killed Friday when an Israeli shell fell on their house in eastern Khan Younis near the border with Israel, in the south of Gaza, the Palestinian Centre for Human Rights (PCHR) said.
A 10-year-old boy was also killed when an Israeli artillery shell hit a street in Gaza City's most eastern neighbourhood, some 200 metres from the border with Israel.
Despite diplomatic attempts to break the cycle, four more projectiles landed in southern Israel on Sunday. One of them was shot down by Israel's new Iron Dome short-range rocket defence system, a military spokeswoman in Tel Aviv said. Another hit an electricity line, causing a power blackout.
Speaking to his cabinet later Sunday, Prime Minister Benjamin Netanyahu said: "Our policy is clear: If the attacks on Israeli civilians and soldiers continue, the response will be much more severe."
He also called the experimental deployment of the Iron Dome "a significant and impressive achievement." Two batteries have been deployed since last week near the southern Israeli cities of Beersheba and Ashkelon and have shot down nine missiles.
Barak has in the meantime cautioned against hurrying into a second "Operation Cast Lead" - the Israeli offensive of the winter of 2008-2009, which curbed rocket and mortar attacks from Gaza for much of the past two years, but killed about 1,400 Palestinians in just three weeks, sparking massive international condemnation. There is no "bang-and-it's-over" solution against the rocket and mortar fire, Barak told Israel Radio. Another large offensive should only be carried out if this was "necessary," he said.
The Israeli government seems unwilling to hurry into a second Gaza war, as does Hamas' political leadership, which is wary of losing its hold of Gaza in case of a major Israeli offensive.