Ukrainian energy facilities came under a “massive attack" from Russia overnight, the Ukraine energy ministry said on Saturday, describing it as the eighth time Russia has launched an assault on energy infrastructure in the past three months.

“The situation in the energy sector remains difficult,” the ministry said in a statement, adding that hourly electricity shutdowns for consumers will be in effect. Two workers were injured and taken to hospital as a result of shelling at one of the facilities, it said.

It was the second attack this week targeting Ukraine's energy infrastructure, according to the ministry.

Air defense systems shot down 12 of 16 missiles and all 13 drones launched by Russia at several regions through the night, the Ukrainian air force said.

Later Saturday, officials in Kharkiv in northeastern Ukraine said three people were killed and at least 18 injured by Russian guided bombs, with at least four explosions heard in the city, the BBC reported.

In recent months, Russia has switched tactics from targeting electricity substations, which Ukraine had become adept at quickly repairing, to trying to flatten entire power stations.

That's destroyed a significant share of power generation in several Ukrainian regions, rendering the country — once a net exporter of electricity — dependent on the EU to keep the lights on. Ukrainian President Volodymyr Zelenskyy recently said Moscow had destroyed half of his country’s electricity-generating capacity since it began pummelling its energy facilities in late March.

EU countries on Friday approved a first tranche of up to €1.4 billion in military aid for Ukraine coming from the proceeds of frozen Russian assets, four diplomats told POLITICO. The formal announcement is expected at a meeting of EU foreign ministers in Luxembourg on Monday.