GAZA CITY (Ma’an) -- Israel's assassination of Hamas military chief Ahmad al-Jaabari is a declaration of war against Gaza Strip, the Popular Resistance Committees said Wednesday.

Al-Jaabari, who ran the al-Qassam Brigades, was killed in an Israeli airstrike on Wednesday afternoon as multiple attacks struck the Gaza Strip.

PRC spokesman Abu Mujahid said all military groups in Gaza were on a state of alert to respond to the killing.

"With this assassination, Israel has opened the gates of hell," he said.

A truce which ended five days of deadly fighting earlier this week is now over, PRC's military wing, al-Nasser Salah Addin Brigades, said in a statement.

This week's cross-border violence left seven Palestinians dead and at least 50 injured, while Gaza factions hit southern Israel with a barrage of rockets.

"Cowardly settlers had better flee to shelters where we will bury them and they will never be able to leave," Abu Mujahid told Ma'an Wednesday.

"The occupation has started the battle and we will respond very fiercely to their crimes."