Crowd of people hanging out on the stairs.
Some people on the stairs.
A crowd of people can also be called some people.
exists e1 s1 x1 x2 x3 x4.(n_stair(x4) & a_topic(x1) & of(x1,x2) & a_out(s1) & Manner(e1,s1) & on(e1,x4) & Actor(e1,x3) & v_hang(e1) & (x2 = x3) & n_people(x2) & n_crowd(x1))
exists x1 x2.(n_stair(x2) & a_topic(x1) & on(x1,x2) & n_people(x1))