At least four people were killed and 10 others were wounded on Wednesday in an explosion at a weapons warehouse in northwestern Syria, according to state media.

The cause of the blast near the town of Sarmada, in Idlib province, was not immediately clear. Such incidents are a relatively common occurrence in the country which has been battered by over a decade of war.

Rescuers dug through the rubble of a Houthi-run prison that was hit in an airstrike in northern Yemen earlier this week, even as the Saudi-led coalition renewed its attacks on rebel areas Wednesday. Rescuers recovered four bodies, raising the death toll at the prison to 23 people, the Houthis said.

The prison collapsed on Monday after it was hit when the coalition targeted the strategic city of Hazm in the northern Jawf province, which in turn prompted the Houthis to launch a wave of missile and drone strikes on southern Saudi Arabia that wounded 73.

Iran's foreign ministry on Wednesday strongly condemned U.S. strikes on its oil tankers, describing the attacks the previous day as a threat to regional security.

"The aggressive actions by the United States against Iranian commercial vessels not only increase the dangers of tensions in the region but are also considered an overt threat to regional and international peace and security," the ministry said in a statement, adding that Iranian forces had targeted U.S. military facilities in the region in "self-defense".

The sun set over this southern Iranian city, and Heydar Sadeghi was where he can be found almost every evening: on a bench next to the shattered remains of his grandson's school. His face was soaked with tears.

A banner strung around the rubble showed the faces of children and teachers killed here by an American airstrike on Feb. 28, the first day of the war on Iran. Among them are Sadeghi's 11-year-old grandson Hami and the boy's mother, Neda Salehizadeh.

In July, Saudi Arabia and the United States bombed Iran-backed militias in Iraq after blaming them for drone attacks on Saudi oil facilities that had been claimed by Yemen's Houthi rebels, another Iranian ally.

Now, regional officials tell The Associated Press that the Houthis helped the Iraqi militias plan and execute the two-day swarm attack, showing a new level of coordination.

Yemen's Iran-backed Houthis reported more than 30 Saudi strikes on several regions on Wednesday, a day after the rebels launched major attacks on their neighbor, injuring dozens of people.

"Saudi enemy aircraft launched 32 airstrikes on various areas across the governorates of Marib, Al-Jawf, Taiz and Hodeida over the past few hours," the rebels' Almasirah television said.

The U.S. military said it destroyed five Iranian oil tankers on Tuesday in response to the latest attacks on its warships and Tehran hit back at American targets in Jordan, the latest burst of back-and-forth strikes that have lurched the sides back toward open hostilities in a more than 6-month-old war.

Following the American strikes, Iran launched missiles toward U.S. targets in Jordan, Iranian state-run media said. Jordan's military said its air defense systems intercepted 18 ballistic missiles launched toward its territory and two others fell in places where no one lives. It said it has no reports of casualties. Jordan is a staunch U.S. ally that hosts American forces, making the kingdom's military bases a target of repeat Iranian strikes. U.S. Central Command said it had no information to offer.

Twelve countries including Britain, Canada and France Tuesday said they would slap sanctions on trade with Israeli settlements in the West Bank, after increasing attacks by Israeli settlers against Palestinian villages in the occupied territory.

"Today, Canada, Denmark, Finland, France, Iceland, Ireland, Norway, Poland, Portugal, Spain, Sweden and the UK confirm their intention to introduce national and/or support European restrictions on trade in goods with settlements which are illegal under international law, or that they are actively considering these and other measures, in accordance with their national procedures," the nations' foreign ministers said in a joint statement.

Iran's Foreign Minister Abbas Araghchi said Tuesday there had been "significant progress" in talks with Oman over the administration of the strategic Strait of Hormuz.

According to an Iranian foreign ministry statement, Araghchi "explained the latest status of Iran-Oman talks on the Strait of Hormuz, reporting significant progress" during a call with his Japanese counterpart.

Israel's military activity in Syria including the detention of hundreds of people could constitute war crimes, United Nations investigators said Tuesday.

"The Commission is deeply alarmed about continued Israeli violations," said commissioner Fionnuala Ni Aolain of the Independent International Commission of Inquiry on the Syrian Arab Republic. "Such acts may amount to war crimes."