Dozens of rockets and mortars from the Gaza Strip hit southern Israel today and an Israeli air strike killed a Palestinian militant, in a sharp escalation of violence after a landmark visit to Gaza by Qatar's leader.
Several foreign workers in Israel were wounded in the rocket fire, and a number of militants were injured in the air attacks, Israeli and Palestinian health officials said.
Hamas security forces were ordered to evacuate their facilities and some southern Israeli schools cancelled classes.
Crossings between Gaza and Israel were shut down following the exchanges of fire in the area.
The Israeli military said 60 rockets and mortars were fired by early morning, and that Israeli aircraft struck Gaza three times. The Popular Resistance Committees said one of its members died in one of the air strikes.
One of the rockets hit a house, causing no injuries, and one of the air strikes struck a mosque in the southern Gaza village of Khouza for the second time in several weeks.
Hostilities have been simmering for weeks, and Israel's defence minister vowed that his country would not accept attacks from Gaza.
Asked if Israel was considering a ground operation in the Palestinian territory, Ehud Barak told Army Radio: "If we have no choice and the fire will continue, then they clearly will be hit harder and nothing is out of the question."
Much of the fighting has been between Israel and smaller militant groups, but the military wing of Gaza's Hamas rulers and a smaller militant group claimed the rocket and mortar fire.
In a statement, Hamas and the Popular Resistance Committees said "these holy missions come in response to the repeated, continuous crimes of the enemy against our people, which killed four and injured 10 in the past 48 hours".
The barrage from Gaza came hours after Qatar's ruler accorded Hamas unprecedented political recognition by becoming the first head of state to visit the largely shunned Palestinian territory yesterday.
Sheik Hamad bin Khalifa Al Thani also promised his oil-rich country would invest hundreds of millions of pounds in construction projects, something that would help to revive flagging popular support for Hamas by generating thousands of jobs in the destitute territory of 1.6 million people.
Israel's border with Gaza has been largely quiet since a major Israeli offensive four years ago, but violence has flared sporadically since.
Despite the recent flare-up, neither side appeared interested in a renewal of large-scale hostilities, and Hamas has largely stayed out of direct confrontation with Israel since the 2009 war. But it is also under pressure from various militant groups, including al Qaida-inspired Salafis active in Gaza, to prove it remains in confrontation with Israel, whose existence it rejects.