Explosions were heard on Sunday in Ukraine's western city of Lviv at about 6 a.m. local time (0400 GMT).

Earlier in the day, air raid alerts went off in Lviv at 3:30 a.m. local time, with residents rushing to bomb shelters for security.

Ukrainian media outlets have yet to release any information about the targets of the airstrikes.

According to the UNN news agency, Kherson in southern Ukraine also reported sounds of explosions, and air alarms continued in most Ukrainian cities and oblasts.