MASYAF, Syria >> The number of people killed in overnight Israeli strikes in Syria has risen to 18 with dozens more wounded, Syria’s health minister said Monday — the largest death toll in such an attack since the beginning of the war in Gaza.

One of the sites targeted was a research center used in the development of weapons, a war monitor said. Syrian officials said civilian sites were targeted.

Israel regularly targets military sites in Syria linked to Iran and the Lebanese militant group Hezbollah. Those strikes have become more frequent as Hezbollah has exchanged fire with Israeli forces for the past 11 months against the backdrop of Israel’s war against Hamas — a Hezbollah ally — in Gaza.

However, the intensity and death toll of Sunday night’s strikes were unusual.

There was no comment from the Israeli military. Israel has carried out hundreds of strikes on targets inside government-controlled parts of war-torn Syria in recent years, but it rarely acknowledges or discusses the operations. The strikes often target Syrian forces or Iranian-backed groups.

Israel has vowed to stop Iranian entrenchment in Syria, particularly since Syria is a key route for Iran to send weapons to Hezbollah.

Israeli strikes hit several areas in central Syria, damaging a highway in Hama province and sparking fires, Syrian state news agency SANA said.

Speaking to reporters, Syrian Health Minister Hassan al-Ghabbash described the strikes as a “brutal and barbaric aggression.” He said the death toll had risen to 18 with nearly 40 wounded.

The Syrian Observatory for Human Rights, a U.K.-based war monitor, said 25 were killed, including at least five civilians, while the others included Syrian army soldiers and members of Hezbollah and other Iran-linked armed groups.

Targeted strikes

One strike targeted a scientific research center in Masyaf, and other sites where “Iranian militias and experts are stationed to develop weapons in Syria,” the observatory said. It said the research center was reportedly used for developing weapons, including short- and medium-range precision missiles and drones.

Minister of Electricity Mohammad al-Zamel said the strikes had caused “truly significant” damage to water and electricity infrastructure.

“This brutal attack targeted civilian targets, and the martyrs were mostly civilians, as were the wounded,” he said.

Muhammad Sumaya, a firefighter with the Hama Fire Brigade, was wounded when shrapnel from one of the strikes hit his foot.

When the strikes began, he said while being treated in the Masyaf hospital Monday, “we moved from one place to another to deal with the fires and work to extinguish them.” While they were working, he said, “a missile landed right next to us.”

Azzam al-Omar, a SANA news agency photographer, said he was hit by shrapnel in the chest when a missile landed while he was photographing the aftermath of a strike.

Local media also reported strikes around the coastal city of Tartous, which the observatory said were the result of air defense missiles falling.

On Monday afternoon, a charred car remained at the scene of one strike and smoke was still rising from some spots where fires had been put out.

Weapons center

The strikes hit an area containing one of the campuses of the Scientific Studies and Research Center. The institute has many sites across Syria, and Masyaf is where the country’s military research organization maintains one of its most important weapons-development facilities, experts say.

Nuclear weapons development experts say the SSRC handles research, development and production of advanced conventional weapons, as well as chemical, biological and potentially nuclear weapons. The United States in 2005 prohibited U.S. citizens and residents from doing business with the center, and in 2007 the Treasury Department froze the assets of center subsidiaries, listing the SSRC as the “Syrian government agency responsible for developing and producing nonconventional weapons and the missiles to deliver them.”

In the past, Israel has acknowledged carrying out hundreds of assaults on targets in Syria that it says are linked to Iran. A series of airstrikes in March near the northern Syrian city of Aleppo killed at least 44 people, including 36 Syrian soldiers and seven members of Hezbollah, the powerful Lebanese militia backed by Iran, the observatory said.

Saudis return

Also on Monday, Saudi Arabia officially reopened its embassy in Damascus, marking a full restoration of relations between the two countries.

Syria was widely shunned by Arab governments over the brutal crackdown by the government of Bashar Assas on protesters in a 2011 uprising that descended into civil war. The breakdown in relations culminated with Syria being ousted from the Arab League.

As Assad consolidated his control over most of the country and the civil war turned into a largely frozen conflict, Arab states moved toward a rapproachement with Damascus.

Saudi Arabia cut off diplomatic relations with Syria in 2012. Last year, soon after Syria was reinstated to the Arab League, the two countries announced they were restoring relations.

This report contains information from the New York Times.