At least seven people were killed when a drone struck a bus in the Russian-controlled Donetsk region of Ukraine, as both sides escalate attacks in the ongoing conflict.

The Russian-installed head of the region, Denis Pushilin, said on Telegram that the bus was traveling between Moscow and Simferopol in Crimea. 'Another 11 people sustained injuries of varying severity, and all are receiving necessary medical care,' he added.

Russia's state news agency Tass reported that the Investigative Committee has opened a criminal investigation under the category of 'terrorist attack,' according to its spokesperson Svetlana Petrenko.

Meanwhile, the governor of St. Petersburg said Ukrainian drones hit infrastructure in several districts, causing damage and wounding several people, as Russian President Vladimir Putin hosts the 'Russian Davos' economic forum in the city.

According to Leningrad Governor Alexander Drozdenko, 50 drones were shot down over the region overnight, and suspected attacks were continuing to be repelled. Drones also hit the city of Michurinsk in the Tambov region, damaging outbuildings at an industrial facility, an apartment building, and a library.

Russia's Ministry of Defence reported that 354 Ukrainian drones were 'intercepted and destroyed' over multiple regions overnight. The attacks came a day after Ukraine's air force reported that Moscow had launched 656 drones throughout the night and into Tuesday morning.

According to the air force, 54 drones and 33 missiles passed through its multilayered air defense system. At least 23 people were killed in those attacks, according to local authorities.

Russia has said its barrage of attacks on Tuesday was in response to a deadly attack on a dormitory in the Russian-controlled Luhansk region two weeks ago.

Source: www.aljazeera.com