12 October 1988
Three Zimbabwean intelligence officers were on trial in Harare, Zimbabwe for attempting to car bomb a house in Bulawayo, occupied by African National Congress (ANC) refugees. Unfortunately for the three Zimbabweans the bomb exploded prematurely and did not accomplish its mission. The car bomb exploded outside this venue on 11 January 1988.
References

O’Malley, P. ‘1988’, from Nelson Mandela Centre of Memory, [online], available at www.nelsonmandela.org  (Accessed: 19 September 2013)|

Kalley, J.A.; Schoeman, E. & Andor, L.E. (1999). Southern African Political History: a chronology of key political events from independence to mid-1997, (Westport: Greenwood) p. 504