(CNN) The Israeli military and Palestinian militants in Gaza exchanged fire on Sunday, hours after a graphic video showing an Israeli army bulldozer scraping the body of a dead man off the ground went viral.

Militants fired more than 20 rockets at Israel by early Sunday evening, according to the Israeli army, making it the largest single assault by militants on Israel in several months.

The army said its Iron Dome aerial defense system intercepted more than half of the launches, with many others landing in open areas. There are no reports of any Israeli injuries from the rockets.

Israel said it launched a series of strikes on targets belonging to Islamic Jihad , the smaller of the two main militant groups in Gaza. Israeli army spokesman Lt. Col. Jonathan Conricus told CNN it was the army's assessment that Islamic Jihad was responsible for the rocket fire.

Islamic Jihad took responsibility in a statement on its official website, saying its military wing, Saraya al-Quds, is responsible for the shelling. It promised to retaliate against any future "aggression."

Among the strikes, Israel says it succeeded in hitting a group of Islamic Jihad operatives preparing to launch a fresh barrage of rockets.

The Palestinian Ministry of Health said four people were being treated in Gaza's Shifa hospital for injuries, though it was not clear whether they were involved in the rocket attacks.

Graphic viral video

The escalation began Sunday morning when the Israeli army says it spotted two men trying to lay an explosive device close to the fence that separates Gaza from Israel. The army -- which released a video it said showed the two men carrying out their operation -- opened fire, killing one of them.

The dead man was identified as 27-year-old Mohammed Al-Naim. The Quds Brigade, the armed wing of Islamic Jihad, said he was one of their fighters.

Gaza sources tell CNN the other man is being treated in a Gaza hospital for severe wounds.

It was the second time in several days that members of Islamic Jihad tried to place an explosive device close to the fence, according to the Israeli army.

As the dead man lay on the ground, a local journalist captured the scene on video, which was subsequently shared widely on social media.

In the video, a group of four men is seen moving toward the body in an apparent attempt to retrieve it. A bulldozer from the Israeli army approached from the opposite direction.

Gunshots could be heard as the bulldozer moved up to the group, which was forced to abandon its effort to carry the body away. Other men nearby could be seen throwing rocks at the vehicle.

The bulldozer's front scoop then appears to come down on top of the dead body as the driver makes several unsuccessful attempts to pick it up.

Eventually the body is seen hanging from the scoop before the bulldozer drives back to the Israeli side of the fence, protected by a tank.

Defense minister: 'That's how we must act'

Israeli Defense Minister Naftali Bennett defended the army's actions in robust terms.

"I'm tired of the tainted left-wing criticism against the 'inhumanity' of using a bulldozer to bring to us the body of a terrorist who tried to murder Israelis. Hamas is holding the bodies of Hadar and Goldin," he said in a statement, referring to the bodies of two Israeli soldiers killed during the Gaza war of 2014.

The statement went on, "I stand behind the IDF that killed the terrorists and collected the body. That's how we must act and that's how we will act. In the face of terrorists, we will act with strength."

An Israeli military official told CNN that using bulldozers to clear the area after a militant attack was standard practice and said they had been used previously to remove bodies, though he admitted it was not the preferred way to do it.

Sunday's escalation came on the final day of the latest visit to Gaza by Qatar's ambassador to the territory, Mohammed Al-Emadi, who discussed a further tranche of Qatari financial assistance for Gazans worth millions.

Aid from Qatar is a key part of multilateral efforts, which also include Egypt and the United Nations, to broker a long-term ceasefire agreement between Israel and Gaza militants, which would see Israel loosen its restrictions on Gaza in exchange for a cessation of violence.

Islamic Jihad is widely seen as opposed to those negotiations, putting it at odds with Hamas, which controls Gaza.