Embed from Getty Images

When a masked gunman burst through the door, sweeping the room with semiautomatic rifle fire, three men tried to stop the slaughter by rushing the attacker. He shot all three.

Without saying a word, the gunman and his accomplice then stepped through the carnage, looking for signs of life and shooting the wounded. They fired 85 rounds and then fled two or three minutes after they arrived.

A previously undisclosed Police Foundation report chronicles in vivid detail the Dec. 2 terrorist attack in San Bernardino, Calif., that killed 14 people and wounded 24 others. A husband and wife who had pledged allegiance to the Islamic State committed the rampage and died hours later in a shootout with the police, the New York Times reports.

The report contains the first official account of how the killers were identified and tracked down, with a handful of officers playing crucial roles. It reveals a wealth of specifics that had not been made public before, including the number of gunshots and other details about the battle that killed the terrorists, the attempt by victims to overwhelm the gunman, the horrors that the officers encountered, and the attackers’ merciless determination to finish off anyone they had not already killed.