July 9 (Reuters) - One person was killed, two power

substations and an oil depot caught fire after Ukraine launched

"tens" of drones in a series of "massive" attacks launched

across several Russian regions, Russian officials said on

Tuesday.

A man died, two other people were injured and several

residential houses were damaged overnight in the Belgorod

region, Vyacheslav Gladkov, the governor of the region that

borders Ukraine, said on the Telegram messaging app.

He said that over the past day four people have died and 20

were injured in various Ukraine's attacks.

A fire broke out at a power substation in the Rostov region

after Ukraine launched "tens" of drones overnight, Vasily

Golubev, governor of the southern Russia region that also

borders Ukraine, said. The fire was extinguished, Golubev said

on Telegram.

A series of explosions were heard in the town of

Kalach-on-the-Don in the Volgograd region in Russia's south, the

Baza Telegram channel, which has sources in Russian law

enforcement, reported.

Andrei Bocharov, the governor of the Volgograd region, said

in a Telegram post that a power substation and an oil depot

caught fire from falling debris from drones which Russian air

defence systems destroyed.

The fire at the substation was promptly extinguished, but

firefighters were still trying to put out the fire at the oil

depot, Bocharov said.

"There is no threat to residential buildings," he added.

A "massive" Ukraine drone attack was also repelled in the

southern Russian Astrakhan region, the region's governor said,

adding there were no injuries.

Several Ukraine-launched drones were also destroyed over the

Voronezh region, several hundred kilometres (miles) south of

Moscow and over the Kursk region, in Russia's southwest that

borders Ukraine, governor said. There was no information on

potential damage.

Russian officials often do not disclose the full extent of

damage inflicted by Ukrainian attacks.

Reuters could not independently verify the Russian reports.

There was no immediate comment from Ukraine.

The attacks come after Russia blasted the main children's

hospital in Kyiv with a missile in broad daylight on Monday and

rained missiles down across Ukraine, killing at least 41

civilians in the deadliest wave of air strikes for months.

Ukraine's President Volodymyr Zelenskiy vowed on Monday that

Kyiv will retaliate.