Israeli armoured personnel carriers gather at the border with Gaza as the latest conflict intensifies and a military showdown looms closer.

An army spokeswoman said all options were on the table, including a possible ground operation to punish those firing rockets into Israel.

(SOUNDBITE) (English) ISRAELI ARMY SPOKESWOMAN LIEUTENANT COLONEL AVITAL LEIBOVICH SAYING:

" We have alerted some of our reserve units and we are considering our next steps currently. We are striking various targets from the air, targets of either caches of rockets, storage's of rockets, underground tunnels used to store rockets and other targets."

Hamas drew its first blood on Thursday morning when one of its rockets killed three Israelis in this apartment, 25 kms from the border.

In Gaza, at least 13 people have so far died, including Hamas military mastermind Ahmed Al-Jaabari, and six civilians, including children.

Both Israel's enemy Iran and neighbour Egypt have condemned the offensive, with Cairo recalling its ambassador from Israel.

There were also protests in the West Bank where Tawfeek Tirawi, a prominent Fatah member, called for the bitter rivals to unite.

"What is happening in Gaza is a crime against our Palestinian people," he says. "We should all be on hand and end the Palestinian rift by going straight to reconciliation."

The Israeli army said 156 targets were hit in Gaza, 126 of them rocket launchers while 200 rockets had struck Israel since the start of the operation.