Hundreds of Palestinians on Monday laid to rest three teenage boys killed in an Israeli airstrike, with their families insisting they had no militant ties as mourners called on Gaza's militant groups to retaliate.

The deaths a day earlier of the teens, whom Gaza's Health Ministry said were 13 and 14 years old, threaten to plunge the area into further violence after a brief exchange of fire between Gaza militants and Israel over the weekend. The Israeli army struck 80 targets in Gaza in response to the heaviest rocket salvos from the Hamas-ruled territory in months.

The teens' bodies were wrapped in Palestinian flags and carried by mourners who shot in the air as they chanted "God is Great."

Aisha Abu Daher said her 14-year-old son Abdel-Hamid had "nothing to do with resistance," referring to the militant factions. Abdel-Hamid and his friends drank tea in the afternoon and rode a donkey cart, a daily habit, and did not come home, she said.

"I went to a wedding, and in the evening I worried when he did not return," she said over the phone from her home in the central Gaza Strip, about 1 kilometer (a half mile) away from the border area. "I don't know why they went or what they were doing there, but I'm sure they were not doing anything bad."

Medics said they recovered the bodies 200 meters (yards) from the fence, which has been volatile for months as the Islamic militant Hamas group has led protests there demanding an end to a decade-old Israeli-Egyptian blockade on Gaza.

The Israeli military said the teens had attempted to damage the border fence and "were apparently involved in placing an improvised explosive device" near it. The area where the incident occurred has never been used as a site for protests.

Fatma Abu Isied said her 13-year-old nephew, Khaled, used to go to the open space along the border to catch birds. "They were there late, and that's why an aircraft hit them...What was their fault? Is this something that deserves an airstrike?" she said outside her brother's home, where women gathered for the funeral.

Hundreds of Palestinians took to the streets Sunday night, burning tires and demanding Gaza militants fire rockets into Israel in retaliation. The sit-ins went on through dawn Monday.

Khaled al-Batsh, an official from Islamic Jihad, a smaller, Iranian-backed group operating in Gaza, said Israel has to lift the blockade if it wants to end the violence. "The lowest price the enemy can pay now is the breaking of the siege," he said during the funeral.

Islamic Jihad, which sometimes acts independently from Hamas, was behind the latest rocket fire into Israel, which it said was in retaliation for the killing of four Palestinians during a Friday protest along the boundary fence.

Israel accused Iranian forces based in Syria of ordering the Palestinian movement to launch the rockets and threatened relation that is "not limited geographically."

Egyptian mediators are working to restore calm, and hope to bring about a national reconciliation between Hamas, which seized Gaza by force in 2007, and the West Bank-based administration of President Mahmoud Abbas.

Hamas says the blockade must be lifted first and has vowed to continue the weekly protests, in which more than 160 Palestinians have been killed since March. A Palestinian sniper killed an Israeli soldier in July.

Israel accuses Hamas of using the large protests as cover to stage border infiltrations and attacks. It says it is defending its border and accuses Hamas of exploiting young protesters and encouraging them to risk their lives in order to increase pressure to ease the blockade.