Israeli aircraft bombed Hamas headquarters before dawn on Saturday, including the office of Gaza Prime Minister Ismail Haniyeh, as armed conflict in the region entered its fourth day.

Hamas later retaliated, firing a rocket at Israel's biggest city Tel Aviv for the third straight day. Police said it was destroyed in mid-air by an Iron Dome anti-missile battery deployed hours earlier, and no one was injured.

In Gaza, Israeli planes shattered Haniyeh's office building -- where he had met with Egyptian Prime Minister Hisham Qandil the day before -- and struck the interior ministry.

Loud explosions regularly rocked the densely populated Palestinian territory, sending plumes of smoke billowing into the sky. The occasional hiss of outgoing rocket fire showed Islamist militants were pursuing their defiance of the assault.