At least that's what the US State Dept. would have you believe....there's more than a few holes in that narrative though, starting with who controlled access to the building the snipers used.
The only Russkie narrative I'm aware of consists of using photos of snipers on a rooftop that wasn't even of a building in the same country, along with a bunch of made up BS, which I suspect you will now share with us uncritically straight from an anti-American Russian propaganda website.