JERUSALEM (AP) — Israel stepped up its attacks on the Gaza Strip, flattening a high-rise building used by the Hamas militant group and killing at least three militants in their hideouts on Tuesday as Palestinian rockets rained down almost nonstop on parts of Israel.

It was the heaviest fighting between the bitter enemies since 2014, and it showed no signs of slowing.

Israeli Prime Minister Benjamin Netanyahu vowed to expand the offensive, while Gaza militants unleashed a fierce late-night barrage of rockets that set off air-raid sirens and explosions throughout the densely populated Tel Aviv m...