Air-raid sirens rang throughout southern Israel — and as far away as the Tel Aviv area — after militants in the Gaza Strip launched dozens of rockets on Wednesday.

Residents braced for an attack after Israel launched air strikes early on Tuesday, which Gaza health officials said killed 13 people, including civilians.

What we know about the rocket attacks

Israel's army said at least 60 rockets had been fired in less than an hour with sirens wailing in the Tel Aviv area some 80 kilometers (50 miles) away from Gaza.

There were no immediate reports of injuries, but local officials said an empty home had been struck in the southern town of Sderot.

Numerous mid-air explosions indicated that air defense systems — part of Israel's Iron Dome system — had intercepted a large number of rockets.

Further exchanges were reported on Wednesday with Israel announcing it would target rocket launch sites of the militant group Islamic Jihad. Plumes of dark smoke could be seen rising from among buildings.

Anticipating retaliatory rocket fire, Israel's military had already urged citizens living in towns within 40 kilometers (25 miles) of Gaza to stay near bomb shelters until Thursday evening.

In a meeting with local leaders near the Gaza Strip, Israeli Prime Minister Benjamin Netanyahu said Israel was "ready for the possibility of an expanded campaign and harsh strikes against Gaza."

What happened the day before

The Israeli military said its "Operation Shield and Arrow" air raids on the Gaza strip on Tuesday had killed three leading members of the militant Islamic Jihad group.

They included Khalil Bahtini, Islamic Jihad's commander for the northern Gaza Strip, Tareq Izzeldeen, the intermediary for the group's branches in Gaza and the West Bank, and Jehad Ghanam, secretary of the group's military council.

Palestinian health officials said the dead had also included the commanders' wives and several of their children. At least another 20 people were said to have been injured.

Islamic Jihad confirmed that the three senior figures were among the dead. The European Union, United States and several other nations list Islamic Jihad as a terrorist organization.

Israel said the airstrikes were a retaliation to rocket fire last week by Islamic Jihad after one of its members died on hunger strike while in Israeli custody.

rc/jcg (AFP, dpa, Reuters, AP)