One of the rockets slammed into central Sderot, causing damage to parked cars and causing nearby pedestrians to go into shock.
The other two missiles landed in open areas outside the rocket-battered town.
Thursday morning, a Kassam struck a kibbutz in the western Negev, causing damage to two homes and sending shards of glass flying into a room where a child was sleeping. No injuries were reported.
Prime Minister Ehud Olmert, whose restraint policy received wide acclaim during his European tour last week, says the cease-fire is becoming more difficult to observe, but stopped short of ordering offensive action in Gaza.
At least 25 Kassam rockets have been fired at Israeli cities and communities since the cease-fire went into effect.