Israel pounded downtown Gaza City with relentless bombardments on Tuesday and further expanded a massive mobilization of reservists as it vowed a retaliation that would “reverberate... for generations” against the Hamas militant group for its surprise weekend attack. The war—which began after Hamas militants stormed into Israel on Saturday, bringing gunbattles to its streets for the first time in decades—has already claimed at least 1,600 lives.

It is only expected to escalate from here, with questions over whether Israel will launch a ground invasion and Hamas threatening to kill captured Israelis if strikes targeted civilians without warning. Israel said that Hamas and other militant groups in Gaza are also holding more than 150 soldiers and civilians hostage. Israel’s military said Tuesday morning that it had regained effective control over its south and the border, breached over the weekend.