Saudi authorities say Houthi drone and missile attacks on four southwestern cities injured 73 people and caused fires at energy facilities, prompting a warning from the Saudi-led coalition that it would respond.

The attacks targeted Abha, Khamis Mushait, Jazan and Najran, according to coalition spokesman Maj Gen Turki al-Maliki. He said the strikes involved dozens of drones and missiles and hit civilian and economic sites. Women and children were among those injured, he added.

Saudi Arabia’s energy ministry said several energy-sector facilities and installations were targeted. The resulting fires led to a temporary halt in some operations, according to a statement cited by the ministry. A satellite image showed smoke rising from a Saudi Aramco bulk plant in Abha.

Al-Maliki described the attacks as a “dangerous escalation” and said the Saudi-led coalition would take “all necessary operational measures to deter” the Houthis.

The Houthi military spokesman, Yahya Sarea, said the attacks were retaliation for more than 120 Saudi air strikes on the Yemeni provinces of Marib, al-Bayda, Hudaydah, Taiz and Jawf over the previous three days. He said the Houthis responded with dozens of ballistic missiles and drones, which he claimed caused significant damage.

The Houthis had also accused Saudi Arabia of bombing a prison in the Yemeni city of al-Hazm on Monday, saying at least 11 people were killed and 20 inmates were missing under the rubble. Those claims were not independently confirmed in the supplied report.

A Saudi-led coalition has backed Yemen’s government against the Houthis during the country’s long-running civil war. The report says an informal four-year ceasefire began to unravel in July after the Houthis announced a maritime embargo against Saudi Arabia and began attacks on Saudi airports, oil facilities and tankers in the Red Sea.

Heavy fighting has also been reported on Yemen’s southwestern coast since Thursday, after a Houthi offensive against pro-government forces near the Bab al-Mandab Strait. The fighting has reportedly killed more than 300 people and displaced 18,500, according to the report.