Russia and Ukraine have traded drone attacks on each other’s infrastructure, causing injuries on both sides.

Moscow said on Thursday that it struck a postal logistics hub, a power substation and a cargo ship, while Ukrainian drones set off fires in an industrial zone in the Russian city of Ryazan, about 200km (125 miles) southeast of the capital.

Russia’s Defence Ministry said on Telegram that its forces had used drones to hit a terminal of Nova Poshta, Ukraine’s largest private delivery company, in the village of Novyi Korotych outside Kharkiv. It said it also struck a 330-kilovolt substation in the Dnipropetrovsk region and a dry cargo ship carrying military equipment in the Black Sea, 52km (32 miles) southwest of the port of Odesa. Ukrainian officials did not immediately confirm the strikes on the postal terminal or the vessel.

Kharkiv Governor Oleh Syniehubov said Russia had attacked the city and 17 settlements in the region over the past day with more than 80 drones, injuring six people, including a child.

In the eastern Donetsk region, Governor Vadym Filashkin said Russian attacks killed four civilians and injured five others on Wednesday, with two people killed in Serhiivka and two in Yasnohirka. Local outlet Novosti Donbasu reported that the two killed in Yasnohirka were women who died when Russian forces struck the village with two glide bombs.

Moscow says the logistics sites it targets serve the Ukrainian military. Nova Poshta facilities have been hit repeatedly, including in an attack on a sorting centre in Kyiv in August that killed three people.

Russian drones also caused large fires in the Bucha district outside Kyiv overnight. A logistics centre was targeted there, and one person was injured.

‘Intensified’ strikes Meanwhile in Russia, Ryazan Governor Pavel Malkov said more than 200 Ukrainian drones had attacked the region overnight.

He said falling debris caused fires at several industrial sites and damaged power lines, cutting electricity to parts of the city, and one person was injured. Malkov later said power had been restored and the fires had been extinguished or contained.

Malkov did not name the sites that were hit. However, footage verified by the independent Russian outlet Astra showed a fire at the Ryazan oil refinery, which is owned by state energy company Rosneft and is among Russia’s largest.

“It’s evident that Ukraine has intensified its strikes on Russian oil refineries” after a brief pause in late October, said Al Jazeera’s Yulia Shapovalova, reporting from Moscow.

She noted that the Yaroslavl refinery had been attacked just two days earlier. Windows were also shattered at a school in Ryazan and classes were cancelled.

Shapovalova said the strikes had not stopped Russian fuel production, but that shortages were occasionally reported “as people rush to gas stations to fill up their cars after the news about attacks on oil refineries”.

Russia, meanwhile, has intensified attacks on Ukraine’s power grid, causing rolling blackouts in Kyiv since mid-October.

“Some people here have not had things like electricity and, more importantly, water for days now,” Al Jazeera’s Audrey McAlpine said, reporting from Ukraine’s capital, Kyiv. “They would say that they can do without electricity, but water is another thing entirely.”McAlpine said city authorities had indicated that heating would not be switched on until temperatures had stayed at minus 5 degrees Celsius for five consecutive days. As temperatures approach zero, she said, the outages become “a matter of life and death”.