KYIV, Ukraine (AP) — Russian forces strafed Ukraine with a fresh barrage of missiles and munition-carrying drones Tuesday, a day after widespread strikes killed at least 19 people in what the UN human rights office described as a “particularly shocking” attack that could amount to war crimes.

Air raid warnings extended throughout the country in the morning, sending some residents back into shelters after months of relative calm in Kyiv and many other cities. The earlier lull had led many Ukrainians to ignore the regular sirens, but Monday’s attacks in the capital and 12 other regions gave them new urgency.

“It brings anger, not fear,” Kyiv resident Volodymyr Vasylenko, 67, said as crews worked to restore traffic lights and clear debris from the city’s streets. “We already got used to this. And we will keep fighting.”

Ukrainian President Volodymyr Zelenskyy was due to address the leaders of the Group of Seven industrial powers by videoconference Tuesday. Germany, which currently chairs the G-7, announced the meeting after Monday’s simultaneous strikes across Ukraine.

The bombardment Tuesday struck both power plants and civilian areas, just as Monday’s attacks did. One person was killed when 12 missiles slammed into public facilities in the southern city of Zaporizhzhia, setting off a large fire, the State Emergency Service said. A local official said the missiles hit a school, residential buildings and medical facilities.

Energy facilities in the western Lviv and Vinnitsya regions also took hits. Although officials said Ukrainian forces shot down an inbound Russian missile before it reached Kyiv, the capital region experienced rolling power outages as a result of the previous day’s deadly strikes.

The governor of the Mykolaiv region, Vitaliy Kim, urged residents to remain in bomb shelters as “there are enough missiles still in the air.”

The State Emergency Service said 19 people died and 105 people were wounded in Monday’s strikes. At least five of the victims were in Kyiv, Mayor Vitali Klitschko said. More than 300 cities and towns lost power, from the capital to Lviv on the border with Poland.

Beside the usual sirens, a new type of loud alarm that blared automatically from mobile phones jolted Kyiv residents early Tuesday. A text message warning of the possibility of missile strikes accompanied the caustic-sounding alert.

Russia’s widespread attacks came in retaliation for a weekend explosion that damaged a bridge linking Russia to the Crimean Peninsula, which Moscow annexed from Ukraine in 2014.

A spokesperson for the office of the UN High Commissioner for Human Rights said Tuesday that strikes on “civilian objects,” including infrastructure such as power plants, could qualify as a war crime.

“Damage to key power stations and lines ahead of the upcoming winter raises further concerns for the protection of civilians and in particular the impact on vulnerable populations,” Ravina Shamdasani told reporters at a UN briefing in Geneva. “Attacks targeting civilians and objects indispensable to the survival of civilians are prohibited under international humanitarian law.”