BBC News:
At least 40 people have been killed in Israel after a major surprise attack with militants crossing into Israel from Gaza during heavy rocket fire.
Several Israelis have reportedly been taken back to Gaza as hostages.
Israel has responded with a wave of air strikes on targets in Gaza killing 161 people, Palestinian officials say.
Israeli Prime Minister Benjamin Netanyahu said Israel is “at war” and vowed that Hamas, Gaza’s rulers, will “pay a price it has never known”.
“This morning Hamas launched a murderous surprise attack against the state of Israel and its citizens,” he said in a video address.
This is one of the most serious escalations in the Israel-Palestinian conflict in years.
The attack by Palestinian militant group Hamas saw fighters cross the perimeter fence just after dawn. At the same time, barrages of rockets were launched from Gaza – some reaching as far as Tel Aviv and Jerusalem.
How the gunmen managed to penetrate one of the most heavily fortified borders in the world is unclear.
The Israeli military has said that dozens of fighter jets are carrying out air strikes on Hamas sites in Gaza, and it has hit 17 Hamas military compounds. It also said it has mobilised tens of thousands of reservists.
The Palestinian health ministry says 161 people have been killed in Israeli strike
