 This reached a point which some automobile stations refused to help Darlington and other Americans.After William F. Courtney, deputy chief of the United States Embassy, received a call from a man identifying himself as DuPont and threatening an imminent attack, a hand grenade exploded outside the embassy.The explosion, which occurred at a time when the building was closed and locked on 3 March, resulted in damage to the embassy sign and the cracking of two windows.