Kyiv, Ukraine(CNN) Russian forces bombarded a residential area in Ukraine's second-largest city with rockets on Monday, killing at least nine people, and several large detonations were heard in the center of the capital Kyiv, as talks between delegates on both sides in Belarus came to a close.
The attack and explosions were launched as Russia becomes increasingly isolated from the rest of the world, particularly Western nations, which have been imposing a rash of sanctions on the country since it launched its invasion of Ukraine last week.
The bombardment in the city of Kharkiv on Monday killed nine civilians, including three children, and wounded 37 others, Mayor Ihor Terekhov said. CNN is reaching out to Russian authorities for comment on the attack.
According to social media videos geolocated by CNN, multiple rockets were seen exploding closely together in a residential part of the Saltivka neighborhood, near a supermarket in the northeast of the city, which the Russian military has frequently targeted.
Ukraine's Prosecutor General Iryna Venediktova described the situation in Kharkiv as "hellish" and shared a video on Facebook of a missile that hit a kitchen window and tore off the leg of a woman, who she said later died in hospital.
As talks between Russian and Ukrainian officials ended early Monday evening, CNN reporters in Kyiv heard several large detonations, followed by sirens going off across the city.
Both sides discussed a potential "ceasefire and the end of combat actions on the territory of Ukraine," Ukrainian presidential adviser Mikhaylo Podolyak told reporters.
Without going into detail, Podolyak said that both sides would return to their capitals for consultations over whether to implement a number of "decisions."
"The parties discussed holding another round of negotiations where these decisions can develop," he said.
Ukraine had earlier demanded an "immediate ceasefire and withdrawal of Russian troops," President Volodymyr Zelensky's office said earlier Monday.
Zelensky earlier downplayed the significance of the talks, which he is not attending in person.
"I do not really believe in the result of this meeting, but let them try, so that no citizen of Ukraine would have any doubt that I, as president, did not try to stop the war when there was even a small chance," he said Sunday.
While Ukrainians have attached little hope in the talks yielding a pathway to peace, the opportunities to deescalate the conflict appear to be quickly shrinking.
Fighting has intensified in Ukraine in the past day in a number of strategic cities. A senior US defense official told reporters on Monday that taking Kharkiv "remains an objective" for the Russians, and "they continue to try to advance on" the southern Ukrainian city of Mariupol. But the Russians have not taken either city yet, the official said.
The official explained that if Russia captures both cities "you can see that would allow them to section off the eastern part of Ukraine," the official said.
On Monday, CNN reporters witnessed at least three "Uragan" multiple rocket launchers in the Russian side of the border south of Belgorod heading towards the Kharkiv front line. They saw three launchers and a loading vehicle with missiles on it.
Russia's larger and far better-equipped military has, however, faced determined resistance across the country, as ordinary Ukrainians and reservists join efforts to defend their families and homes, frustrating Moscow's attempts to swiftly take control of key cities.
Western allies have been increasing its assistance to Ukraine through funds and weapons to aid its defense.
Ukraine said its air force shot down a cruise missile launched at the city from Belarus Sunday, and claimed a successful drone attack against a Russian BUK surface-to-air missile system near the capital.
But Western military assessments caution that Ukrainian forces cannot holdout indefinitely.
On Monday, it appeared the the bulk of Russian ground forces were more than 30 kilometers (about 19 miles) north of Kyiv, according to an intelligence update by the the UK's Ministry of Defense. The advance of those troops was slowed by stiff Ukrainian resistance at the nearby Hostomel airfield, "a key Russian objective for day one of the conflict," the ministry said.
The Russian military announced what it described as an "open and safe" corridor for civilians to leave the capital on Monday, while repeating a baseless claim that the Ukrainian government was using residents as a "human shield."
And while Ukrainian troops appear to be holding ground in the country's north, Russian forces have made some advances to the south. On Sunday Russian troops took control of Berdyansk -- a port city of 100,000 people on Ukraine's southern coast, and the site of a small naval base.
The ongoing Russian assault has inflicted widespread suffering and casualties on the Ukrainian population. More than half a million refugees have fled Ukraine to neigboring countries, according to the UN's refugee agency. The number of known civilians killed in Ukraine stands at 352, with 14 of those children, Ukraine's Ministry of Interior said Sunday.
Ukraine's General Staff of the Armed Forces accused Russia of hitting civilian areas. "In violation of the norms of international humanitarian law, the occupiers have insidiously inflicted missile strikes on residential buildings in Zhytomir and Chernyhiv," a statement said on Monday.
CNN is unable to independently verify these claims.
Pressure is intensifying on the Kremlin as Western allies of Ukraine try to prop up the country with weapons and as Russia faces financial turmoil, with the ruble in free fall.
Russian President Vladimir Putin on Sunday raised the stakes by ordering his country's nuclear forces to be placed on high alert.
Later on Sunday, Belarus renounced its non-nuclear status in a referendum, after the former Soviet nation became a launch pad for Russia's invasion in Ukraine last week. The vote in favor of a new constitution could theoretically allow Russia to place nuclear weapons back in Belarus for the first time since the fall of the Soviet Union, when Belarus gave up its stockpile and became a nuclear free zone.
Addressing journalists at a polling station in Minsk, Belarusian President Alexander Lukashenko said he could ask Putin to "return the nuclear weapons" Belarus gave away if the West transferred any nuclear weapons to Poland or Lithuania.
Ukrainian intelligence also indicated Belarus could be preparing to "participate directly" in the invasion of Ukraine, according to two sources close to the Ukrainian government. Lukashenko said last week that Belarusian troops could join the invasion "if it becomes necessary."
Meanwhile, the UK said it will provide an additional $53 million in humanitarian aid to Ukraine and British leaders plan to introduce legislation in Parliament aimed at clamping down on Russian money laundering and fraud.
And Australian travel bans and targeted financial sanctions against Putin and senior members of his government went into effect Monday, the country's Prime Minister Scott Morrison confirmed in a statement.
South Korea and Singapore on Monday also announced new sanctions on Russia.