Serebrianka forest: Russian Grad BM-21 rocket hits the Ukrainian trench with soldiers

Video shows a fragment of the battle near Kreminna. While the assault units of the Russian group are moving forward along the trench, the drone operators are hitting the Ukrainian Armed Forces infantry.
After the strike, you can see how one surviving Ukrainian militant runs to his rear.
P.S. Soldiers from the field correct that the hit was caused by a Grad shell.
https://en.wikipedia.org/wiki/Serebrianka,_Donetsk_Oblast
https://en.wikipedia.org/wiki/BM-21_Grad#Projectiles