The Saudi-led military coalition in Yemen carried out several air strikes on the Houthi-held capital Sanaa on Thursday after the Iranian-aligned movement claimed responsibility for drone attacks on Saudi oil installations.

The Sanaa strikes targeted nine military sites in and around the city, residents said.

Rubble filled a populated street lined by mud-brick houses, a Reuters journalist on the scene said. A crowd of men lifted the body of a women, wrapped in a white shroud, into an ambulance.

Houthi-run Masirah television quoted the Houthi health ministry as saying six civilians, including four children, had been killed and 60 wounded, including two Russian women working in the health sector. A coalition spokesman did not immediately respond to a Reuters’ request for comment.

Medical charity Medecins Sans Frontieres said two hospitals it supports in Sanaa took in 48 injured and four dead people as a result of the strikes.

A coalition statement carried by the Saudi-owned Al Arabiya TV, said the Sunni alliance struck military bases and facilities and weapons storage sites with the aim of “neutralising the ability of the Houthi militia to carry out acts of aggression”.

“The sorties achieved its goals with full precision,” the coalition said. It had urged civilians to avoid those targets. One resident reported a strike near a densely-populated district, where flames and clouds of smoke could be seen. A car was half-buried under rubble and twisted metal on a street lined with bystanders.

“There was an air strike near us, in the middle of an area packed with residents between Hael and Raqas (streets),” Abdulrazaq Mohammed said. “The explosion was so strong that stones were flying. This is the first time our house shakes so much.”

Sanaa has been held by the Houthi movement since it ousted the internationally recognised government of Abd-Rabbu Mansour Hadi from power there in late 2014. The coalition has previously targeted suspected drone and missile storage sites in the city.

Saudi Arabia’s deputy defence minister on Thursday accused Iran of ordering Tuesday’s armed drone attack on two oil pumping stations in the kingdom. “The terrorist acts, ordered by the regime in Tehran and carried out by the Houthis, are tightening the noose around the ongoing political efforts,” Prince Khalid bin Salman tweeted.

The Houthis said they were responsible for the attack, which did not disrupt oil output or exports. The group denies being a puppet of Tehran or receiving arms from Iran.

The head of the Houthis’ Supreme Revolutionary Committee denied that Iran directed the strike and said the movement manufactures its drones locally. Tehran also denies providing arms to the Houthis.

“We are not agents for anyone,” Mohammed Ali al-Houthi said. “We make decisions independently and do not take orders for drones or anything else.” The coalition described the drone attack as a “war crime”.

The UAE said on Wednesday that the western-backed coalition, of which it is a main member, would “retaliate hard” for any Houthi attacks on coalition targets.

The Sanaa air strikes and renewed fighting in Yemen’s Hodeidah port that breached a UN-sponsored truce in the Red Sea city, could complicate peace efforts to end the four-year war that has killed thousands, many of them civilians, and pushed the country to the brink of famine.