Gaza militants fired at least one Grad rocket into the southern Israeli town of Netivot Thursday evening, following a long lull in violence.
Police were looking into reports of a second explosion.
The Color Red early warning system did not go off, giving the resident no indication of the coming attack.
One woman suffered shock and no damage was reported.
The rocket marked the first such attack on Netivot in nine months. The last Grad rocket to hit the city exploded near a synagogue, and caused some damage.
Netivot Mayor Yehiel Zohar contacted the Israel Defense Forces demanding to know why the early warning system failed to work.
The unusual Grad attack came hours after hundreds of demonstrators gathered on both sides of the Gaza border to mark one year since Israel's offensive in the Strip last winter.
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