The freighter La Coubre, chartered to transport cargo to Cuba, was in Havana's port when it exploded around noon. The ship was reportedly carrying munitions to aid the Cuban revolutionary government. As the ship started unloading, a series of explosions rocked the area, sending debris flying and creating a massive fireball that could be seen miles away. Initial reports indicated that lightning struck the ship, but this theory was quickly dismissed as investigators began to uncover evidence suggesting a direct cause associated with its cargo. The local media and government officials grappled with the ramifications of the explosion while confusion reigned in the immediate aftermath. Emergency services were called in to rescue victims and to control the blaze, with many civilians and foreign nationals among the injured. The Cuban government, led by Fidel Castro, faced international scrutiny, as they were already navigating strained relations with the United States and other Western powers during the height of the Cold War.

In the ensuing days, investigations were launched to ascertain not only the cause of the explosion but also the implications of storing such dangerous cargo close to populated areas. As the event unfolded, it created a ripple effect in political discourse, emphasizing the need for better safety protocols concerning ammunition handling and storage. The aftermath saw Cuba bolster its military preparedness, further aligning with other socialist regimes, particularly the Soviet Union. Initial theories of sabotage gained traction among some, stoking fears of external interference, while others pointed to a lack of safety measures, ostensibly exacerbated by the rapid changes in the maritime policies under Castro's leadership.