The rocket landed in Kibbutz Zikim, a communal farm not far from the Gaza-Israel border and the town of Ashkelon, police spokesman Micky Rosenfeld said.
A series of Palestinian rocket attacks hit Israel over the weekend, including one which struck a factory in the western Negev Friday. This came after the cabinet declared a "special situation" in Sderot and in other communities bordering the Gaza Strip due to the ongoing barrage.
Earlier Sunday, Israel Defense Forces arrested 25 Hamas members, including a member of Parliament, in overnight raids in the West Bank city of Nablus, Palestinian officials said.
Those arrested included lawmaker Ahmad al-Haj Ali, as well as a former deputy cabinet minister and two city council representatives, all Hamas members, Palestinian security officials said.
The IDF said troops made overnight arrests in an operation targeting Hamas operatives in Nablus.
Hamas, a militant Islamic movement with ties to Syria and Iran, has largely been driven underground in the West Bank since it took over the Gaza Strip in June, defeating the forces of the rival Fatah movement.
Mahmoud Abbas, Fatah's leader and the Palestinian president, has ruled the West Bank since then and his moderate government has been moving ahead with peace talks with Israel and cracking down on Hamas.
The Israeli arrests came two days after Abbas' security forces carried out a similar sweep targeting Hamas supporters in Nablus. Hamas put the number of detainees at 26.
The raid also came in wake of a pro-Hamas rally in Gaza on Saturday that drew about 250,000 people and was a major show of force for the Islamic group.
Israel arrested dozens of Hamas lawmakers in the summer of 2006, after Hamas forces captured Israel Defense Forces soldier Gilad Shalit and killed two others in a cross-border raid near Gaza.
Talks on a prisoner swap have stalled and Shalit remains in captivity.
Ahmad Bahar, a senior Hamas official in Gaza, said Sunday that the lawmaker's arrest overnight brought the number of Hamas parliamentarians held by Israel to 46.