JERUSALEM -- Militants in the Gaza Strip fired dozens of rockets Wednesday into southern Israel, sending civilians rushing into bomb shelters but causing no casualties. The Israeli military said it was the largest rocket barrage since 2012, when it launched an eight-day air campaign in Gaza it said was aimed at stopping the attacks.
The Israeli military said its aircraft targeted "29 terror sites in the Gaza Strip" in retaliation late Wednesday.
Gaza health official Ashraf Al Kedra said nobody was hurt in the Israeli strikes that he said targeted training sites used by the Islamic Jihad and Hamas militant groups.
Israel's military said Gaza militants fired more than 40 rockets at Israel in two hours, with three intercepted by its "Iron Dome" missile defense system and eight hitting populated areas. The others fell in open areas. The barrage set off air-raid sirens in southern communities within range of the rockets.
"This retaliation was precise and prompt. We targeted the infrastructure that serves the terrorists while they train, plan and implement their hideous attacks. They will not be permitted to conspire in the safety of their terrorist temples," Israeli Military spokesman Lt. Col. Peter Lerner said.
Earlier, Israeli tanks fired at "terror infrastructure" in Gaza, the Israeli military said, saying it confirmed at least one hit. Residents in the Beit Hanoun area of Gaza said they saw an Israeli strike hit a rocket launcher squad.
The rocket barrage from Gaza began Wednesday afternoon. Israeli police spokesman Micky Rosenfeld said one rocket exploded near a gas station and another near a public library in two separate communities in southern Israel.
In Gaza, the Islamic Jihad militant group said it fired 20 rockets to avenge the deaths of three of its members killed in an Israeli airstrike the day before. The Israeli military said they fired at soldiers with mortars.
Lerner, the military spokesman, called Wednesday's rockets "an escalation... Yesterday they attacked our troops and today it is our civilians."
Another Gaza militant group, the Popular Resistance Committees, said they fired several rockets as well.
The Iranian-backed Islamic Jihad has killed dozens of Israelis in suicide bombings and other attacks over the years. Israel's military said it had targeted the militants on Tuesday after they fired at Israel.
Gaza militants have fired thousands of rockets and mortar rounds at Israel over the past decade. Attacks have declined since an eight-day Israeli offensive against Gaza militants in 2012 but rocket fire still persists. Israeli aircraft periodically strikes militants that launch the rockets. The military said Wednesday's barrage was the biggest since that campaign.
Israeli Prime Minister Benjamin Netanyahu vowed to continue striking the Gaza rocket launcher squads.
"We will continue to thwart (rocket attacks) and hit those that want to harm us, and we will act against them with great force," Netanyahu said. "Last year, the number of rockets fired from Gaza was the lowest in a decade but that is not enough. We will continue to act to ensure the security of the citizens of Israel in the south and in the entire country."
The Israeli military said Gaza militants fired 32 rockets toward Israel so far this year prior to those fired today, compared to 49 in 2013. Militants fired rockets at southern Israel on an almost daily basis before that.
An Associated Press reporter standing on a balcony saw more than a dozen rockets being fired from the southern outskirts of Gaza City.
Last week Israeli special forces captured a ship in the Red Sea that was carrying rockets and other weapons that Israel says were supplied by Iran and destined for Gaza.
Visiting British Prime Minister David Cameron condemned the rocket fire. "Let me absolutely clear about these attacks from Gaza, we condemn them completely," he said.
"These attacks are completely indiscriminate aimed at civilian populations and that is a demonstration of how barbaric they are," Cameron said.
U.S. State Department spokeswoman Jen Psaki said that Washington "condemns in the strongest terms today's rocket attacks into Israel by terrorists from the Gaza Strip .... Israel, like any nation, has a right to defend itself."
U.N. Secretary-General Ban Ki-moon also strongly condemned the multiple rocket attacks and "deplores the severe escalation of violence," U.N. spokesman Stephane Dujarric said. "He urges all actors to exercise maximum restraint to prevent further incidents that could bring greater escalation and destabilization in the region."