Israeli artillery firing shells into Gaza after every 30 seconds: army

Like clockwork, every 30 seconds Israeli artillery goes into action against a barely visible target somewhere in Palestine's Gaza.

In a statement on Thursday, the army said it has bombarded Gaza with approximately 6,000 munitions containing a total of 4,000 tonnes of explosives since Saturday when it began striking Hamas targets.

Troops have deployed 150 mm artillery guns in fields along the border with Gaza, placing them a few metres apart, near the towns of Netivot and Sderot which were overrun by Hamas in their weekend onslaught.

Each time a salvo is fired, the ground shakes and a deafening noise fills the air.

On the front lines near the Gaza border, Netivot and Sderot are used to being targeted by rockets fired from Gaza, a tiny, densely populated enclave that is home to 2.4 million people.

The army has set up roadblocks to stop infiltration by Palestinian fighters into southern Israel.

In the skies above, Apache helicopter gunships fly at low altitude, before briefly breaching the airspace of Gaza.

Massive build-up

"Soon, there won't be anyone left to fight, to attack us, to spoil our lives," said Tom, a 24-year-old reservist, deployed in the area.

Tom said he travelled from his home in Rishon Le Tzion near Tel Aviv to join up with his unit, in which his younger brother Adam also serves.

"I don't know what I will do. But one thing is certain: we will wipe them off the map," said Tom, still wearing shorts, a T-shirt and sandals, unlike Adam who is in uniform and toting an M-16 machine-gun.

Israel has vowed to "crush" Hamas after fighters from the group stormed across the border and killed 1,200 people.

Israel has retaliated by pounding Gaza with air strikes and artillery bombardments that have razed entire city blocks, with Palestinian officials reporting more than 1,450 killed, most of them civilians.

Six days since the offensive took Israel by surprise, its army has kept pounding the densely populated Gaza with artillery shells and air strikes, as it prepares for a possible ground invasion.

Israel has massed forces, tanks and other heavy armour around Gaza and called up 300,000 reservists.