Mourners in Deir Al Balah in Gaza carry the bodies of two of the three teenage boys killed in an Israeli airstrike.
CNN —  

An Israeli airstrike killed three young Palestinian teenagers near the fence that separates Gaza and Israel on Sunday evening, according to the Palestinian Ministry of Health.

The health ministry named the boys as Khalid Abu Sa’ed, 14, Abdel Hameed Abu Zahir, 13, and Mohammed al-Satari, 13. They were from the city of Deir Al Balah in the central Gaza Strip.

The Israel Defense Forces (IDF) said one of its aircraft opened fire on three people who appeared to be trying to plant explosives.

“Three Palestinians approached the security fence in the southern Gaza Strip, attempted to damage it and were apparently involved in placing an improvised explosive device adjacent to it. In response an IDF aircraft fired towards them,” the Israeli military said in a statement.

Sami Abu Zohri, a leader of Hamas, the militant group that runs Gaza, rejected the IDF’s account, saying in a statement that the three boys had been “peacefully protesting near the eastern border of the besieged enclave.”

Hanan Ashrawi, a member of the executive committee of the Palestine Liberation Organization, described the deaths in a statement as a “clear war crime in violation of international law and international humanitarian law.”

Nickolay Mladenov, the UN’s Special Coordinator for the Middle East peace process, tweeted, “Such tragedies must be avoided at all costs. Children must be protected, not exposed to violence or put in danger.”

Hundreds killed in clashes

Tensions between Israel and Gaza have been high for months.

Ongoing weekly clashes along the border fence have left more than 200 dead since March, according to the Palestinian Ministry of Health.

In addition, there have been a series of sharp escalations involving exchanges of rocket fire by Gaza militants and air-strikes by the Israeli Air Force.

The latest flare-up happened Friday evening when Islamic Jihad militants fired more than 30 rockets into Israel, according to the IDF, soon after the deaths of five Palestinians in clashes with Israeli soldiers along the fence.

Many of the rockets were intercepted by Israel’s Iron Dome aerial defense system, the IDF said, and no one was hurt in the barrage.

An Israeli military spokesman on Saturday accused Iran of orchestrating the attack from Syria, saying the launches had been carried out “under guidance, instructions and incentives” given by the Islamic Republic.

The IDF said the military responded with air-strikes on 80 targets in Gaza, including some belonging to Hamas. Israel says it holds Hamas ultimately responsible for everything that happens in Gaza.

But IDF spokesman Lt. Col. Jonathan Conricus suggested these strikes would not be Israel’s only response to the rocket barrage.

In a rare move, he threatened the Israeli military would also carry out airstrikes in Syria against Syrian and Iranian targets in response, viewing Iran as responsible for Islamic Jihad’s decision to launch rockets at Israel.

Israel seldom acknowledges carrying out strikes in Syria, and it is very rare for it to warn of those strikes in advance.

CNN’s Oren Liebermann contributed to this report.