JERUSALEM - Israel launched a massive airstrike on the Gaza Strip on Tuesday, hitting 35 targets and a tunnel crossing into Egypt and Israel, said the Israeli military in a statement.

The statement said the airstrike was in response to a barrage of 28 mortar shells that Gaza militants fired at Israel on Tuesday morning.

The attack from Gaza caused no major damage except for a man who was slightly injured in the hand, the statement said.

The airstrike was carried out by Israeli fighter jets and aircraft which struck over 35 targets in seven terrorist sites, said the statement.

The sites belong to Hamas, the Islamist Palestinian organization that runs Gaza, and the Palestinian Islamic Jihad, a local Islamist group, it claimed.

"The IDF (Israeli Defense Forces) targeted six military compounds, munition storage warehouses, naval targets and terrorist headquarters," the statement said.

As part of the strike, the army also hit "an offensive terror tunnel" belonging to Hamas in the area of the Kerem Shalom crossing near Rafah, it said.

The tunnel started within the Gaza Strip, crossed into Egypt's Sinai Desert before stretching into Israeli territory, it added.

But media reports from Gaza said what was hit by Israel was in fact a smuggling tunnel used to transfer goods to the besieged Palestinian enclave.

The Israeli military insisted that the tunnel was "dual-purposed - designated for terror purposes, as well as to transfer munitions to Egypt."

During the airstrike, more projectiles, mortars and rockets were fired from Gaza at Israel, triggering sirens in the regional councils of Hof Ashkelon and Sha'ar HaNegev, as well as the Ashkelon Industrial Area and the city of Sderot.

There were no further reports of injuries or damage as result of the strikes from both sides.

The Israeli army blamed the Islamic Jihad for carrying out the mortar attack on Tuesday morning. It was believed to be in retaliation for an earlier Israeli attack, which killed three Islamic Jihad fighters in Gaza on Sunday.

An Israeli military spokesperson said in a statement that the mortar attack was "a severe, dangerous and orchestrated act of terror, aimed at civilians and children."

The spokesperson accused Iran of funding the group, citing that the Tuesday's attack used Iran-made ammunition.

"The IDF will not allow any harm to the safety of Israeli civilians or Israeli sovereignty, and will continue to operate with determination against all kinds of terrorism," said the spokesperson.

Israeli civilians in the areas surrounding the Gaza Strip were instructed to stay close to shelters.

The violence followed a serious escalation in the border area between Gaza and Israel over the past months. Israeli forces have killed at least 110 Palestinians in the weekly Palestinian demonstrations starting from March 30.