Gun battles forced shops and schools to close in Yemen’s capital Sanaa on Sunday as residents warned a three-year rebel alliance was collapsing into a “street war”.

The Iran-backed Houthi rebels’ partnership with powerful ex-president Ali Abdullah Saleh appeared to have fallen apart after he reached out to a Saudi-led coalition fighting the insurgents.

The Houthis’ political office on Saturday accused Saleh of staging a “coup” against “an alliance he never believed in”.

On Sunday, Saleh loyalists cut off a number of streets in central Sanaa and deployed heavily in anticipation of Houthi attacks, as security sources said clashes this week had left some 60 dead across the capital and at its international airport.

Saleh loyalists renewed a bid to seize control of Al-Jarraf district, a stronghold of the Iran-backed Houthis, who fortified their positions with dozens of vehicles mounted with machineguns, witnesses said.

They said the Houthis had brought reinforcements from their northern strongholds and deployed them in the south of the capital.

The Houthis seized the home of rebel interior minister Mohammed Abdullah al-Waqsi, who is close to Saleh, killing three of his bodyguards and detaining others, Saleh sources said.

And Houthi rebels killed Mohammed al-Zarka, a tribal leader close to Saleh, in Omran just north of the capital and members of his family, the same sources said.

Sanaa residents said they had barricaded themselves in their homes to avoid snipers and shelling as clashes flared up around key ministries where the two sides had been working together just days before.

The education ministry cancelled classes on Sunday, normally the start of the school week, and witnesses said some bodies of those killed in previous clashes this week were still lying in the streets.

Iyad al-Othmani, 33, said he had not left his house for three days because of the clashes.

Mohammed Abdullah, a private sector employee, said his street had been cut off by militiamen and he was staying home to avoid checkpoints.

“Sanaa is becoming like a ghost town. There is a street war and people are holed up in their houses,” said an activist who works with the International Organisation for Migration in Sanaa.

“If the confrontation continues, many families will be cut off” and stranded in their homes, he warned.

Three years after they joined forces to drive the government of President Abd-Rabbu Mansour Hadi from Sanaa, the collapse of the Houthi-Saleh alliance is a key shift in Yemen’s complex war.

Saleh ruled Yemen as president for 33 years after the 1990 unification of north and south Yemen .

A longtime ally of Saudi Arabia, he waged six separate wars against the Houthis, Zaidi Shias who hail from northern Yemen .

Saleh resigned under popular and political pressure in 2012, ceding power to his then-vice president Hadi, who now lives in exile in Saudi Arabia.

In 2014, Saleh announced he had joined forces with the Iran-backed Houthis, seizing the capital and setting up a parallel government as Hadi’s administration fled Sanaa. That triggered a Saudi-led Arab force to intervene to prop up Hadi’s government, an escalation in a war that has since killed more than 8,750 people and dragged the country towards what the United Nations calls the world’s worst humanitarian crisis.