Palestinian witnesses say Israeli aircraft are striking Hamas militant targets in the southern Gaza Strip.
The late-night local time strikes follow a rocket launched from Gaza that set off air-raid sirens in southern Israel and sent residents rushing to bomb shelters before the rocket fell in open ground.
There was no immediate comment from the Israeli military.
The rocket strike and airstrikes ended a brief lull that had prevailed for most of the day after an earlier exchange of heavy fire.
The cross-border fighting yesterday was triggered by a rocket fired from Gaza that slammed into a house in central Israel and wounded seven people.