KHARKIV, Ukraine (Reuters) - Russian air strikes killed at least four and injured eight others in Ukraine's northeastern city of Kharkiv on Sunday, local officials said.

Reuters correspondents at the scene of the strike saw a recreation area destroyed after what rescuers at the scene said was a powerful blast, followed by a second, "double tap" strike about fifteen minutes later.

A man's corpse lay under the rubble of what just over an hour previously was a busy lakeside restaurant area on a sunny day. A woman stumbled around in shock looking for her handbag in the wreckage.

"The occupiers attacked the area where local residents were relaxing," Kharkiv's governor, Oleh Syniehubov, said on the Telegram messaging app.

In recent weeks, Kharkiv city and the region of the same name have been under constant attack by Russian missiles and guided bombs as Russian troops have launched an offensive in the northeast of the region.

(Reporting by Max Hunder in Kharkiv and Pavel Polityuk in Kyiv; Editing by David Goodman and Frances Kerry)