People running in a marathon in running clothes.
The marathon just began
People in running clothes running in a marathon does not necessarily mean that the marathon just began.
exists e1 e2 x1 x2 x3 x4 x5.(a_topic(x1) & in(e1,x3) & Theme(e2,x5) & Actor(e2,x4) & v_run(e2) & n_clothes(x5) & (x3 = x4) & n_marathon(x3) & Actor(e1,x2) & v_run(e1) & (x1 = x2) & n_people(x1))
exists e1 s1 x1.(n_marathon(x1) & a_just(s1) & Manner(e1,s1) & Actor(e1,x1) & v_begin(e1))