Many police in shielded helmets are gathered underneath a railway.
The police are arresting a bunch of people.
Just because the police have their gear on does not necessarily mean they are arresting a bunch of people.
exists e1 s1 x1 x2 x3.(underneath(e1,x3) & n_railway(x3) & Theme(e1,x1) & v_gather(e1) & in(x1,x2) & n_helmet(x2) & a_shielded(s1) & Theme(s1,x2) & n_police(x1) & n_quantity(x1))
exists e1 x1 x2 x3.(n_police(x1) & Theme(e1,x2) & Actor(e1,x1) & v_arrest(e1) & of(x2,x3) & n_people(x3) & n_bunch(x2))