Israeli jets struck the Gaza Strip late on Thursday for the third time in as many days, moderately wounding four Palestinians, security and medical officials said.
Security officials and eyewitnesses said that the Israeli aircraft hit three targets; two in the Gaza City area and a third in Khan Younis, further south.
All of the sites were bases used by Hamas and other militant groups, they said.
The Israeli military confirmed that its aircraft had attacked Gaza but a spokeswoman could not immediately give details. The strikes came at the end of a day in which at least five projectiles were fired into southern Israel from the Hamas-ruled Gaza Strip.
"There were two rockets fired in the general direction of one of the kibbutzim," police spokesman Micky Rosenfeld told AFP on Wednesday evening, without reporting damage or injuries.
An additional three unspecified "projectiles" were fired from Gaza into southern Israel, also causing no casualties, the Israeli military said.
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A spokeswoman could not say if they were rockets or mortar rounds.
On Wednesday night Israeli aircraft targeted three tunnels, two used for smuggling in southern Gaza and one "used for terrorist activity" in the north of the Palestinian territory.
"The tunnels were targeted in response to the firing of rockets at Israel's southern communities during the previous day," the military said.
Palestinian medical sources said five people were moderately wounded in those strikes and two people were reported missing.
On Tuesday Israeli air raids hit what the military called two "weapons manufacturing sites" in northern Gaza. Palestinian medical sources said one woman was moderately injured.
The past three days of rocket fire and retaliatory raids represented the first significant uptick in violence in the area since April, when tensions rose after an anti-tank missile fired from Gaza hit an Israeli school bus, killing a teenager.
Israel responded with a series of airstrikes that killed at least 19 Palestinians in the deadliest violence since Israel's devastating 22-day assault on the Gaza Strip in December 2008-January 2009.
The bus attack and its aftermath raised fears of another such ground campaign but on April 10 Hamas declared a return to the truce that ended Israel's "Operation Cast Lead" in January 2009, and the calm has since largely held.