Friendly Fire- Russians Open Fire On Buddy

Ukrainian drone footage shows an incident in which a Russian fire team makes contact with what is reported to be a fellow Russian soldier. For whatever reason, the two men open fire on their buddy, killing him. They then walk by his body for a closer look before continuing on their way. It's not clear if a failed challenge and password lead to them mistaking him for a Ukrainian, or possibly some sort of verbal altercation or preexisting interpersonal strife was resolved in that moment.