Ukrainian officers who coordinated Kiev regime troop movements in the area apparently believed that doing so during nighttime would keep Ukrainian infantry hidden from the prying eyes of Russian aircraft and drone surveillance.
Their mistake became apparent when 122mm rockets launched by Russian BM-21 Grad MLRS units started raining upon Ukrainian militants, killing at least 30 of them and sending the rest scurrying for cover.
This short video released by the Russian Ministry of Defense features the highlights of this attack.