The Israeli Air Force struck seven targets in the Gaza Strip early Friday morning in response to a second day of rocket fire on southern Israel.

According to the IDF Spokesperson’s Unit, IAF aircraft hit four sites in the southern Strip and three in the north.

“We will continue to retaliate to the aggression emanating from the Hamas-run Gaza Strip,” said IDF spokesman Lt. Col. Peter Lerner. “Militants attacking Israel from the Gaza Strip will not feel safe, will pay the price and will find that their actions are futile.”

Rocket-alert sirens rang out across southern Israel for a second straight night Thursday, as over a dozen rockets were fired from Gaza and a several-hour-old ceasefire with Islamic Jihad threatened to unravel.

Two missiles, including one heading for a populated area of Netivot, were shot down by Iron Dome anti-rocket batteries, the IDF said.

Other missiles hit open spaces in the Sderot, Shaar Hanegev and Sdot Hanegev areas. No injuries or damage were reported.

Earlier in the evening, two rockets were launched at the Ashkelon region, sending residents scurrying for shelter. Both landed in open areas.

Lerner said 18 rockets were fired at Israel all day on Thursday, including eight that hit open areas, two that were shot down, and eight that failed to clear the Strip.

However, media reports on the number of rockets varied, with some tallying 16 since the ceasefire began in the early afternoon.

The IDF said Thursday night it was deploying Iron Dome batteries to Beersheba and Ashdod, indicating it may be expecting hostilities to widen. Both cities are on the outer edge of the range of most Gazan rockets and are generally targeted during larger escalations in violence.

Gaza terror group Islamic Jihad denied it launched the attacks earlier in the evening and it wasn’t immediately clear who fired the rockets. Ceasefire declarations have not always been honored by terror groups and the barrage raised doubts about the ceasefire offer.

Islamic Jihad had claimed responsibility for a barrage of over 60 rockets that hit Israel on Wednesday evening. Israel responded to those attacks by hitting 29 sites in Gaza from the air Wednesday night.

Thursday morning saw more sporadic rocket fire, drawing a response by Israeli planes, after which Islamic Jihad announced a ceasefire, ostensibly brokered by Egypt.

After the ceasefire announcement, Israeli officials said the military would respond to “calm with calm,” according to Israel Radio.

Three Gazans were also injured Thursday evening after attempting to launch a rocket from the northern strip. The rocket likely malfunctioned and exploded on the ground, sources in Gaza said.

Palestinian Authority President Mahmoud Abbas earlier condemned the escalating violence, including rocket fire from Gaza. ”We condemn all military escalation, including rockets,” he said at a press conference in Bethlehem with British Prime Minister David Cameron.

His statements came hours after Prime Minister Benjamin Netanyahu criticized Abbas for initially condemning Israeli airstrikes on the Strip, but not the rocket fire from Gaza that prompted them.

Thursday morning saw five rockets fired at southern Israel from the Strip. Two failed to reach Israel, while three set off warning sirens in Ashdod and Ashkelon.

The Iron Dome anti-missile system downed one of those rockets over Ashkelon, while two others fell in unpopulated areas.

Times of Israel Staff and AP contributed to this report