At the instant of the explosion, Che Guevara was in a meeting in the INRA building. After hearing the blast and seeing the debris cloud from a window overlooking the port area, he drove to the scene and spent the next hours giving medical attention to the scores of crew members, armed forces personnel, and dock workers who had been injured, many of them fatally. Thirty minutes after the first explosion, while hundreds of people were involved in a FAR-organized operation to rescue victims and secure the ship, a second even more powerful explosion occurred, resulting in many additional fatalities. Father John McKniff (a Roman Catholic missionary priest) and nurse Gloria Azoy, both of whom had rushed to the scene and were assisting the wounded and giving last rites, were thrown to the pavement by the second explosion. Although stunned, they survived amid the clouds of expended explosives and dust and continued their work. Father McKniff, given his long work as a missionary in Cuba and elsewhere, is currently being considered for sainthood by the Catholic Church.
Although the exact toll of the La Coubre explosions remains uncertain, it is estimated that there were at least 75 dead and approximately 200 injured, with some sources giving figures that are much higher. Cuban Government spokesmen and some other sources occasionally have put forward the claim that this event was an act of sabotage carried out by William Alexander Morgan acting on orders from the CIA. However, it has never been confirmed that this was, indeed, done by the CIA.