- An international monitor told the UN there were 500 explosions recorded in Ukraine Wednesday night into Thursday morning.
- The US embassy said Russian "shelling" hit a kindergarten and injured two teachers.
- NATO's chief blamed Russia for "trying to stage a pretext for an armed attack against Ukraine."
An international security monitor on Thursday told the United Nations Security Council that roughly 500 explosions were recorded in Ukraine between Wednesday evening and Thursday morning.
Yaşar Halit Çevik, who oversees the monitoring mission in Ukraine for the Organization for Security and Co-operation in Europe, or OSCE, told the UN Security Council on Thursday that there were hundreds of explosions recorded along the frontlines over the past day, according to multiple news reports.
Reuters journalist Michelle Nichols reported on Thursday that Çevik told the Security Council that after late Thursday morning, around 30 explosions were recorded. The OSCE said on Wednesday that it recorded only 76 explosions, suggesting that tensions erupted overnight and appear to have simmered.
On Thursday, the US Embassy in Ukraine blamed the explosions on Russian "shelling" in Ukraine's eastern Donbas region, and said Russian fire "hit a kindergarten, injured two teachers, and knocked out power in the village."
"The aggressor in Donbas is clear – Russia," the US embassy said on Twitter.
Earlier this week, Russian President Vladimir Putin claimed without evidence that a "genocide" is occurring in the Donbas region, where Kremlin-backed rebels have been at war with Ukrainian forces since 2014, Insider's John Haltiwanger reported.
The rebels have blamed Ukraine for the recent explosions in the area controlled by Moscow-backed separatists, which Kyiv has denied.
NATO Secretary-General Jens Stoltenberg said there is a concern "that Russia is trying to stage a pretext for an armed attack against Ukraine."
Meanwhile, President Joe Biden on Thursday said that there is a "very high" risk of a Russian invasion of Ukraine in the next few days.
His words come amid claims from Moscow that it has reduced its troop presence along the border — claims both the US and NATO have firmly rejected.
This story is developing. Please check back for updates.