Russia carried out its second large-scale drone and missile attack on Ukraine in four days, Ukrainian officials reported on Tuesday, once again targeting power infrastructure amid subzero temperatures. The strikes appear to disregard ongoing U.S.-led peace efforts as Moscow’s invasion approaches its fourth anniversary.

Ukrainian President Volodymyr Zelenskyy said on social media that Russian forces launched nearly 300 drones, 18 ballistic missiles, and seven cruise missiles across eight regions overnight.

A strike in the northeastern Kharkiv region killed four people at a mail depot, while several hundred thousand households in the Kyiv region were left without electricity, Zelenskyy added.

Kyiv has endured extended power shortages, with daytime temperatures falling to minus 12 degrees Celsius, approximately 10 degrees Fahrenheit. Ice-covered streets and the hum of generators have become a daily reality for residents, despite measures to restore electricity.

Mayor Vitali Klitschko said the previous night’s attacks caused the largest electrical outage the capital has experienced to date, compounding the humanitarian strain during winter conditions.