EL MOZOTE, El Salvador — After the soldiers left, the survivors crept out from the ravines and the caves where they had hidden from the slaughter to see a land laid to waste. Some tried to quickly bury the charred bodies of their mothers and their children. Then they fled.

For decades, these witnesses grieved in silence over the massacre in the Salvadoran village of El Mozote and nearby hamlets. But after a recent court decision, they have finally begun to speak out publicly, describing in grim detail the four days in December 1981 when Salvadoran military units, trained and equipped by the United States, killed almost 1,000 people in the largest single massacre in recent Latin American history.

“Miraculously, God spared us so that we could tell what happened,” said Dorila Márquez, 61, sitting on the covered terrace of the rebuilt house she fled with her husband and small children when she was 25. As the young family ran that day, they heard screams and gunfire behind them.

Survivors like Ms. Márquez had faint hope they would ever see justice. But a provincial judge has reopened a long-dormant trial over the massacre at El Mozote, ordering the retired military commanders who once sowed terror across El Salvador to hear charges of war crimes in his 40-seat courtroom.