Palestinian witnesses say Israeli airstrikes have hit a series of targets across Gaza City, shortly after the assassination of the top Hamas commander.

Hamas security officials say two Hamas training facilities were among the targets in the Wednesday afternoon bombings. Plumes of smoke are rising in the air, and people are running in panic through the streets as militants angrily fire their weapons in the air.

Earlier, Israel killed the head of the Hamas military wing, Ahmed Jabari, in an airstrike. In all, Palestinian officials say six people have been killed in the Israeli attacks.

Israel says the airstrikes are the beginning of a broader operation, launched in response to days of heavy rocket fire from Gaza.