On 21 August 1971 , while the opposition ( Liberal Party ) was having their '' miting de avance '' in Plaza Miranda , 2 fragmentation grenades exploded . It took 9 lives and left more than 100 people seriously wounded . Some Liberal Party candidates were seriously injured including Jovito Salonga , who nearly died and was visually impaired . Suspicion of responsibility for the blast initially fell upon Marcos , whom the Liberals blamed for the bombing ; however , in later years , prominent personalities associated with the event have laid the blame on the Communist Party of the Philippines under José María Sison . In his autobiography , Salonga states his belief that Sison and the CPP were responsible . Based on interviews of The Washington Post with former Communist Party of the Philippines Officials , it was revealed that " the ( Communist ) party leadership planned -- and three operatives carried out -- the attack in an attempt to provoke government repression and push the country to the brink of revolution ... ( Communist Party Leader ) Sison had calculated that Marcos could be provoked into cracking down on his opponents , thereby driving thousands of political activists into the underground , the former party officials said . Recruits were urgently needed , they said , to make use of a large influx of weapons and financial aid that China had already agreed to provide . " A month of " terrorist bombings " of public facilities in Manila and Quezon City culminated on 22 September with a staged assassination attempt on Defense Secretary Juan Ponce Enrile
2 fragmentation grenades exploded
Plaza Miranda bombing
Martial law in the Philippines