The strike was apparently carried out in response to a barrage of at least 30 Qassam rockets fired Wednesday morning at Gaza vicinity communities.
Military sources confirmed that a vehicle traveling near the strike's original target – a terror cell involved in the firing of rocket attacks – was accidentally hit, adding that the incident was being looked into.
Palestinian sources in the Strip reported that the three civilians killed were the members of one family – 13-year-old Amir Yazgi, his father and uncle. According to the sources, the missile was apparently directed at Islamic Jihad gunmen, but accidentally hit a jeep traveling behind their vehicle.
The residents of Sderot and Ashkelon woke up Wednesday to a continuing rocket barrage, as at least 30 Qassam rockets were fired from northern Gaza towards the two cities. Several people suffered from shock.
Most of the rockets landed in open areas, but a loud explosion was heard coming form Ashkelon's industrial area. One of the rockets landed in Kibbutz Zikim, south of Ashkelon. There were no reports of injuries, but some of the kibbutz hothouses were damaged.
A worker at Ashkelon's southern industrial zone told Ynet, "We ran to the fortified rooms every few minutes, we heard the explosions around us, and it was terrifying. Now it has quieted down, but it's still very tense."
Hamas has escalated the rocket fire over the past 24 hours, following IDF operations in the Gaza Strip, which resulted in 19 dead Palestinians gunmen, including the son of senior Hamas figure Mahmoud al-Zahar.
"We shall respond to the crimes committed by the Israelis in the only language which they understand," al-Zahar threatened Tuesday.
Hanan Greenberg contributed to this report