Waves of explosive-laden suicide drones have struck Ukraine’s capital, setting buildings on fire and sending people scurrying for shelter.

The concentrated use of drones marks the second barrage in as many weeks – after months where air attacks had become become a rarity in central Kyiv.

Energy facilities were struck, and one drone slammed into a residential building, killing four people, authorities in Kyiv said.

The attack drones appeared to include Iranian-made Shaheds.

Intense, sustained bursts of gunfire rang out as the aircraft buzzed overhead, as soldiers tried to shoot them down.

Ukraine has become grimly accustomed to such attacks nearly eight months into the Russian invasion, and city life resumed as rescuers picked through the debris.

Previous Russian air strikes on Kyiv were mostly carried out with missiles.

Mayor Vitali Klitschko said Monday’s barrage came in successive waves of 28 drones – in what many fear could become a more common mode of attack as Russia seeks to avoid depleting its stockpiles of long-range precision missiles.

Five drones plunged into Kyiv itself, said Ukrainian Prime Minister Denys Shmyhal.

In the Kyiv region, at least 13 drones were shot down, all of them flying in from the south, said a spokesman for the Ukrainian Air Force, Yurii Ihnat.

One strike appeared to target the city’s heating network, hitting an operations centre.

Another slammed into a four-storey residential building, ripping a large hole in it and collapsing at least three apartments on top of each other.

Four bodies were recovered, including those of a woman who was six months pregnant and her husband, Mr Klitschko said. An older woman and another man also were killed there.

An Associated Press photographer who was out shooting morning scenes of Kyiv caught one of the drones on camera, its triangle-shaped wing and pointed warhead clearly visible against the blue sky.

Ukrainian President Volodymyr Zelensky said in a social media post: “The whole night, and the whole morning, the enemy terrorises the civilian population.

“Kamikaze drones and missiles are attacking all of Ukraine.

“The enemy can attack our cities, but it won’t be able to break us.”

Andrii Yermak, head of the Ukrainian president’s office, said in a social media post that Shahed drones were among those used in the strike.

Mr Zelensky, citing Ukrainian intelligence services, has previously alleged that Russia has ordered 2,400 of the Shahed drones from Iran.

Russia has rebranded them as Geran-2 drones – meaning geranium in Russian. A photo of debris from one of Monday’s strikes, posted by Mr Klitschko, showed the word Geran-2 marked on a mangled tail-fin.

Iran has previously denied providing Russia with weapons, although its Revolutionary Guard chief has boasted about providing arms to the world’s top powers.

Iranian-made drones have been repeatedly used by Russia elsewhere in Ukraine in recent weeks against urban centres and infrastructure, including power stations.

They are comparatively cheap, costing in the region of 20,000 US dollars (£17,000).

Their use in swarms presents a challenge to Ukrainian air defences, said Mr Ihnat, the air force spokesman. Western nations have promised to bolster Ukrainian air defences with systems that can shoot down drones but much of that weaponry has yet to arrive and, in some cases, may be months away.

After months during which strikes in central Kyiv were rare, early morning strikes last week put Kyiv as well as the rest of the country back on edge.

Russian President Vladimir Putin said those strikes were in retaliation for the bombing of a bridge connecting the Crimean peninsula with the Russian mainland.

Mr Putin blames Ukraine for masterminding the blast, which suspended traffic over the bridge and curtailed Moscow’s ability to supply Russian troops in the occupied regions of southern Ukraine.

The strike on Kyiv comes as fighting has intensified in the eastern regions of Donetsk and Luhansk in recent days, as well as the continued Ukrainian counteroffensive in the south near Kherson and Zaporizhzhia.

Mr Zelensky said in his Sunday evening address that there was heavy fighting around the cities of Bakhmut and Soledar in the Donetsk region.

The Donetsk and Luhansk regions make up the industrial east known as the Donbas, and were two of four regions annexed by Russia in September in defiance of international law.

On Sunday, the Russian-backed regime in the Donetsk region said Ukraine had shelled its central administrative building in a direct hit. No casualties were reported.