Russia launched missiles on busy Ukrainian cities on Monday killing civilians and cutting out power and heat with its most widespread air attacks since the start of the war.

The United States has described the attack as “horrific strikes” as the missiles tore into intersections, parks and tourists sites in the capital Kyiv.

Also, explosions rock other cities which include Lviv, Ternopil and Zhytomyr in western Ukraine, Dnipro and Kremenchuk in the centre, Zaporizhzhia in the south and Kharkiv in the east.

Reuters reported that Ukrainian officials said at least 11 people were killed and scores injured, plunging the country into darkness.

Thousands of residents ran to bomb shelters as air raid sirens rang out through the day. The bombardment of dozens of cruise missiles fired from air, land and sea was the biggest wave of air strikes to hit locations away from the front line, at least since the initial volleys on the war’s first day, February 24.

Russian President Vladimir Putin said he had ordered “massive” long range strikes after an attack on the bridge linking Russia to the annexed Crimean peninsula over the weekend, and threatened more strikes in future if Ukraine hits Russian territory.

“To leave such acts without a response is simply impossible,” Putin said, alleging other, unspecified attacks on Russian energy infrastructure.

Ukrainian military intelligence said the Russian attacks were ordered in early October. “The objects of critical civil infrastructure and the central areas of densely populated Ukrainian cities were identified as targets,” it said.

President of Ukraine Volodymyr Zelenskiy said they were deliberately timed to kill people, as well as to knock out Ukraine’s power grid. His prime minister said 11 major infrastructure targets were hit in eight regions, leaving swaths of the country with no electricity, water or heat.

“They are trying to destroy us and wipe us off the face of the earth,” Zelenskiy said.