By Guy Faulconbridge and Lidia Kelly MOSCOW (Reuters) -Russian forces on Wednesday advanced further into Ukraine's northern region of Sumy, threatening the regional capital after taking more than 150 square km (58 sq miles) of the area in less than two weeks,

At least seven people were killed and 41 others were injured in massive Russian strikes across Ukraine overnight, which targeted civilian and energy infrastructure.

Russian forces are advancing in the northern Ukrainian region of Sumy, bringing the regional capital within range of their drones and artillery, according to Ukrainian officials and analysts.

The Ukrainian city of Sumy was once again the target of a devastating Russian missile strike on June 3, with four people killed and 28 others, including three children, injured. Russia launched the attack during rush hour.

A Russian artillery attack on Ukraine's northeastern city of Sumy on Tuesday killed four people and injured 28, including three children, officials said.President Volodymyr Zelenskiy announced the updated death toll of four in the city in his nightly video address.

Russia launched a massive drone and missile barrage across Ukraine in a major retaliatory strike, days after Kyiv damaged key Russian bombers.

Senior Ukrainian officials visited Washington on Tuesday seeking U.S. support against Russia, as Kyiv showed its ability to fight on by setting off an explosive device under a bridge that has become a symbol of the Kremlin's claims on Ukrainian territory.

Ukraine President Volodymyr Zelenskyy has condemned a Russian attack on the city center of Sumy, saying that's all one needs "to know about Russia’s ‘desire’ to end this war.”

Reports of an imminent Russian summer offensive and troop build ups on Ukraine's border are raising alarms in Sumy Oblast and fears that a large-scale assault could be on the horizon. Russian President Vladimir Putin on May 22 said he had ordered his military to create a "security buffer zone" along the border,