"The truth is I could not reach that man; if I could have, I would have," R. Umar Abbasi wrote in a first-person account Wednesday, a day after the paper's haunting cover sparked widespread outrage.
He said he was waiting for a train when he saw, out of the corner of his eye, a "body flying through the air and onto the track."
"I just started running. I had my camera up - it wasn't even set to the right settings - and I just kept shooting and flashing, hoping the train driver would see something and be able to stop," Abbasi wrote. "I had no idea what I was shooting. I'm not even sure it was registering with me what was happening. I was just looking at that train coming.
"The victim was so far away from me, I was already too far away to reach him when I started running," he said. "The train hit the man before I could get to him, and nobody closer tried to pull him out."
He said he didn't even look at the pictures. He just turned them over to his editors and the police.
Now, he said he's haunted by the events.
"All I can hear is that man's head against that train: Boom! Boom! Boom!" he wrote.