WATCH: Missile Siren Sounds in Downtown Tel Aviv

Air raid sirens ring through Tel Aviv as the Iron Dome anti-missile system intercepts rocket.

DPA - Air raid sirens sounded in the seaside metropolis of Tel Aviv, Israel's biggest population center, early Wednesday, preceding the sound of two blasts.

It was not immediately clear whether the blasts were the sound of a missile striking or that of one being downed in mid-air by Israel's Iron Dome missile defense system.

Ilan Assayag

The incident came as Israel continued pounding militant targets in the Gaza Strip early Wednesday, after the second night of a major offensive.

The bombing targeted 160 sites, a military spokeswoman in Tel Aviv said, bringing the total since Israel launched Protective Edge before dawn Tuesday to 435.

Protective Edge came in response to a renewed wave of rockets out of the Gaza Strip, for some of which Palestinian group Hamas has claimed responsibility. It is the first time since 2012 that Hamas has done so, claiming that intervening attacks were sent up by groups working outside its control.

But the cycle has been exacerbated this time by the recent deaths and presumed murders, first of three teenaged Israeli boys, followed by that of a Palestinian boy in the West Bank in recent weeks.

Armed groups in Gaza have fired 225 rockets during this cycle. One of which reached the town of Hadra, about 116 kilometres north of Tel Aviv, the furthest a missile from Gaza has ever reached. It landed in the yard of a house. 

Israel's Iron Dome downed some 40 missiles, some of them over Israel's biggest cities.

So far there have been no fatalities in Israel. In the Gaza Strip, at least 23 Palestinians have been killed, among them civilian bystanders and several children. More than 122 have been reported injured.