JERUSALEM (AP) -- Israeli jets bombed Gaza hours after militants from the territory on Tuesday fired more than 25 mortar shells toward communities in southern Israel in what appeared to be the largest single barrage since the 2014 Israel-Hamas war.
The Israeli military said no one was hurt and that most of the mortar shells were intercepted by the Iron Dome defense system, though one of the shells landed near a kindergarten shortly before it opened.
The high volume of projectiles came as tensions have been running high along the Israel-Gaza border and a fierce Israeli response was expected.
"Israel will exact a heavy price from those who seek to harm it and we see Hamas as responsible for preventing such attacks," Prime Minister Benjamin Netanyahu said following the barrage.
Shortly after that warning, Israeli jets began dropping bombs at what security officials in Gaza called Islamic Jihad militant training site. Smoke was seen rising near the town of Deir al-Balah in the coastal strip and the Israeli military said the explosions there were related to its activity. No injuries were reported.
Islamic Jihad was believed to be behind the attacks with a green light from Hamas, the militant Islamic group that runs the Gaza Strip.
"We are sticking to the right of return as well as responding to the Zionist crimes," said Khaled al-Batsh, an Islamic Jihad leader in Gaza.
Ismail Radwan, a Hamas official, said the barrage proved that the "resistance is capable of hurting the occupation and it proved this today by responding to its crimes."
Radwan spoke as a two fishing boats carrying students and medical patients set sail out of Gaza City's port, aiming to break 11 years of naval blockade that Egypt and Israel imposed after the militants violently took control of the coastal territory.
The expedition would be a new way of challenging the blockade but also raises the possibility of more confrontation and violence as Israel bars any boats from Gaza reaching farther out than a six-nautical-mile radius into the Mediterranean Sea. Hamas acknowledged it was mostly a symbolic act.
It also marks eight years since Israeli commandos raided a Gaza-bound aid flotilla, killing nine pro-Palestinian Turks and sparking an international outcry against the blockade.
In southern Israel, angry residents complained about how vulnerable they felt after 15 years of rocket fire threats from neighboring Gaza, which will likely put pressure on the government to retaliate harshly.
Adva Klein, a resident of Kibbutz Kfar Aza, said she only got about two hours of sleep because of the frequent incoming fire and the sirens warning of them. Other residents reported machine gun fire from Gaza as well.
"It's been a really scary morning," said Adele Raemer, a resident of Kibbutz Nirim.
Defense Minister Avigdor Lieberman said he was convening the top military brass at his Tel Aviv headquarters to discuss the situation.
The border area has been tense in recent weeks as the Palestinians have held mass protests aimed at lifting a blockade imposed by Israel and Egypt after Hamas seized power in 2007.
Israeli fire has killed more than 110 Palestinians, most of them during the Hamas-led protests, which climaxed on May 14.
On Sunday, Israeli shelling killed three Palestinian militants from the smaller Islamic Jihad group after the troops found a bomb planted along the border. The Islamic Jihad vowed retaliation.
On Monday, a tank fired at a Hamas position in the Gaza Strip, killing one man and wounding another, after Israeli troops came under fire on the frontier while apprehending two armed Palestinians.
Hamas has vowed to continue the border rallies. Israel says it is defending its border as well as its communities nearby. It accuses Hamas of trying to carry out attacks under the cover of protests.