Three loud explosions rocked Jerusalem shortly after air raid sirens wailed across the city on Tuesday night, AFP correspondents said.
The sirens sounded at about 1900 GMT, with at least four bright flashes lighting the sky southwest of the city, a correspondent said.
The Israeli army had no immediate comment on the attack which took place as Israel began a waging major campaign against Hamas militants in the Gaza Strip.
Media reports also spoke of sirens sounding north of Tel Aviv for the first time as Hamas militants stepped up their battle against Israel.