Several hundred people gathered in Cuba’s capital on Thursday to remember the 73 killed in the Oct. 6, 1976, terrorist bombing of a Cubana de Aviacion jet.

Civil servants, airline employees, students, Communist Party officials and families of the victims marked the 40th anniversary of the attack with a procession at Havana’s Colon cemetery.

The event was led by Gerardo Hernandez, one of the “Cuban Five” intelligence officers who spent years behind bars in the U.S. before being released as part of the normalization of ties between Washington and Havana.

“It’s more than an anniversary, more than a day on the calendar. Their mothers, their fathers, their siblings waiting for them at home never saw them again,” Hernandez said of the people killed in the explosion.

Cubana de Aviacion Flight 455 was scheduled to fly from Guyana to Havana with stops in Trinidad, Barbados, and Kingston.

Two anti-Castro militants who boarded the plane in Trinidad and got off in Barbados brought aboard two toothpaste tubes filled with plastic explosives and wired to timers.

The explosives went off shortly after the plane left Barbados bound for Kingston.

The aircraft was carrying 57 Cubans – including 24 members of the national fencing team – along with 11 Guyanese nationals and five North Koreans.

Venezuela prosecuted the two men who planted the bomb and two other Cuban exiles accused of masterminding the attack: Luis Posada Carriles and Orlando Bosch.

Both Bosch and Posada were convicted, but the latter managed to escape in 1985, while the former remained in Venezuela until his conviction was overturned in a 1987 trial.

Bosch, who had been sentenced in the U.S. to 10 years in prison for a 1968 incident in which he fired a bazooka at a Polish freighter docked in Miami, returned to Florida in 1988 and was arrested for violating his parole.

He was subsequently turned over to U.S. immigration authorities for deportation, but then-President George H.W. Bush intervened to block the deportation and allow Bosch to remain in the United States, ignoring a Justice Department finding that he had taken part in more than 30 terrorist acts.

Bosch died in 2011 in Miami. Posada, who is wanted in Venezuela, is thought to be living in South Florida after his April 2011 acquittal on U.S. federal charges of perjury, fraud and obstruction of justice.

The Cuban-born Venezuelan citizen was accused of lying when he applied for political asylum and U.S. citizenship. Federal prosecutors said he perjured himself when he denied under oath that he was involved in bomb attacks on Havana hotels in 1997.

An Italian tourist died in one of the blasts.

Posada acknowledged in a 1998 interview with The New York Times that he helped organize the bombings of hotels in Cuba, but the U.S. Army veteran and former CIA operative later claimed that his poor grasp of English caused him to misspeak in his exchange with reporter Ann Louise Bardach