New Delhi, Feb. 12 -- A Russian drone smashed into a home in Ukraine's northeastern Kharkiv region overnight, killing a father and his three small children, officials said Wednesday. The family's pregnant mother was wounded but survived.

The strike completely destroyed the brick house and set it on fire, trapping the family under the rubble, according to the Kharkiv regional prosecutor's office.

The 34-year-old father and his three children - 2-year-old twin boys and their 1-year-old sister - were killed, while rescue workers pulled out the mother alive, prosecutors said.

During the almost four years since Russia launched all-out war on its neighbor, and despite a new push over the past year in U.S.-led peace efforts, Ukrainian civilia...