April 21 1962 / AP Wirephoto / A WATCH FROM THE WINDOW - An East German policeman keeps watch from an open window on two West Berlin policemen manning a post along the communist wall at Bernauer Strasse in Berlin today. Earlier the West Berlin and East German police exchanged gunfire and tear gas grenades in this area in an incident touched off by western holiday visitors taking a look at the wall. On communist side of the wall windows in buildings have been walled up leaving only a few open for police posts. berlinwall