Two National Guard pilots were killed in Cyprus on Saturday after the single-engine military plane in which they were flying crashed into a vacant apartment building near Limassol and went up in flames, authorities said. The PC-9 plane was flying from Paphos to Agios Ioannis, close to Nicosia, to take part in a military exercise when at 10.15 a.m. witnesses saw it circling above Kolossi village in what was probably an attempt to make an emergency landing. The Swiss-built aircraft then crashed into a two-story building which was vacant as its British owners were away due to renovations. Twenty-nine-year-old Fotis Constantiniou, who was to attend his engagement party yesterday, and Feraios Kouloumos, 33 years old, were both killed. Authorities say the accident happened under unusual circumstances as the plane was flying at an exceptionally low altitude, was off course and the pilots had failed to make contact with any of the nearby flight centers. Cypriot authorities have requested the help of the Greek air force in finding the causes of the accident.