Minyan in stairwell

My apartment building is entirely frum, and has a minyan in its stairwell. There are two groups of men, separated by half of a flight of stairs. The stairs are 4 ft. 6 in. high, and 4 ft 8 in. long, making it a tel hamislaket. The two groups cannot see each other. Are the steps a mchitza to be mafsik tziruf for a minyan?

Because of the difficulties of the necessary Corona distancing, we have no choice but to rely on the more lenient opinions, which allow 10 men to join as a minyan, if there is 1 who sees both groups (I hope, medically, that each group is comprised only of members of 1 family!), even if they're on different levels, and he should be the shaliach tzibbur. The apartment building is not considered r'shut harabbim to separate them. Once they are considered a minyan, then people from other floors can also join in and are considered tfila b'tzibbur. May all the sick be speedily healed!