Air raid sirens were sounded in Tel Aviv on Tuesday, while live television showed an apparent midair interception by Israel's Iron Dome anti-missile system.

Israeli officials had been expecting an increase in rocket fire from the Gaza Strip after Hamas officials vowed revenge for an airstrike on the home of one of their leaders in the southern Gaza town of Khan Younis. Hamas announced that the strike had killed six people, with children among the dead.

"The Khan Yunis massacre ... of children is a horrendous war crime, and all Israelis have now become legitimate targets for the resistance," Hamas spokesman Sami Abu Zuhri said. According to local residents, the deaths happened when the house came under attack for a second time.

It was unclear who the dead were, although the AFP news agency quoted an emergency services spokesman as saying that children were among the injured.

Reuters quoted local residents as saying that people had gathered on the roof of the building after the first strike.

Reservists placed on call-up list

There was no immediate comment from the Israeli military. Meanwhile, the government announced that it had given permission to call up some 40,000 more reservists, although it called the move purely a contingency measure.

A spokesman for the Israel Defense Forces (IDF) provided more details earlier on Tuesday about Operation Protective Edge, a military offensive targeting alleged militants in the Gaza Strip.

According to army spokesman Peter Lerner, 80 rockets and mortars (an example is pictured above) were launched from Gaza into Israel on Monday alone.

Israel's response came in the form of air and naval attacks that were aimed Gaza homes said to belong to militants, concealed rocket launchers and other sites. About 50 targets in Gaza were hit, according to the IDF.

"They chose the direction of escalation," army spokesman Peter Lerner said. "So the mission will go on as long as we feel it is necessary to carry it out. We don't expect it to be a short mission on our behalf."

Lerner added the air assault could be expanded with a "ground mission if required," but all attacks would stop if Hamas ceased launching rockets on Israel.

The surge in violence has come as tensions rise on both sides over the murder of three Jewish teenagers, which Israel has blamed on Hamas, and the killing of a Palestinian youth, apparently in revenge.

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