As day six of Russia’s invasion into Ukraine got underway, Russia continued to focus on Ukraine’s two largest cities: Kharkiv and the capital of Kyiv. Tuesday brought the second straight day of shelling in Kharkiv. Explosions tore through residential areas, and a maternity ward was moved to an underground shelter.

“As a result of air strike, the building of the regional administration has been partially destroyed, and the buildings next to the administration,” Yevhen Vasylenko, a representative of the Emergency Situations Ministry in Kharkiv region, said. “People are under the ruins, we have pulled out bodies of at least six people, around 20 people are injured.”

As Ukrainian officials work through the rubble in Kharkiv, a 40-mile-long convoy featuring hundreds of Russian tanks and other vehicles was captured on satellite cameras heading towards Kyiv. The satellite photos, from U.S.-based Maxar Technologies, showed the convoy was about 17 miles away from the center of Kyiv.

“The defense of the capital is the most important,” Ukrainian President Volodymyr Zelenskyy said Tuesday. “I decided to appoint a professional military general as the head of Kyiv’s City Military Administration during the war time, in order to guarantee defense of the city, to block the enemy’s approaches to our capital, to make sure Kyiv’s residents have everything that is necessary.”

Russia’s advances on Ukraine’s two largest cities come as Russia is becoming more and more isolated. Economically, Russia was dealt another blow with oil company Shell announcing it is pulling out of the country. Back in the U.S., members of Congress worked to become less dependent on Russian oil.

“Putin’s not going to stop until it gets to be unbearable at home,” Sen. Lindsey Graham (R-SC) said. “The one thing we’re not doing that would affect him the most is sanction the oil and gas sector of Russian economy.”

“We need to consider stopping the flow of energy from Russia to the United States and enlist our allies in the same cause,” Sen. Richard Blumenthal (D-CT) said Monday. When asked what that would do to gas prices, Sen. Blumenthal said, “Our imports from Russia are relatively new and we can help to supplement the supplies going to our allies.”

Russia is also experiencing more diplomatic isolation. Dozens of diplomats walked out of two different United Nations meetings Tuesday, both times as Russian Foreign Minister Sergey Lavrov was speaking.