Audio obtained by Spanish media of the conversations between the operators of both trains and the control center sheds light on the series of decisions leading up to the collision at about 8:53 a.m., near the train station in Urda. NBC News has not been able to independently verify the authenticity of the audio.

After the computer system went down, the control center told the Renfe train operator to resume its journey “at normal speed,” according to an audio clip.

“At normal speed? OK,” the operator responded.

“OK, we’ll talk later,” the controller said before signing off.

Several minutes later, someone from the control center called the Iryo train to authorize it to also continue on its normal journey, according to an audio clip.

The operator of the Iryo train, which was ahead of the Renfe train, called back seven minutes later to say she had been unable to restart the train. “I’m still stopped at the entrance signal,” she said, according to the audio clip. The control center then told her to restart the train when she can and to call back if she has further problems, according to the audio. Several minutes later, the Renfe train collided with the back of the Iryo train.