The assault happened the day that Ms. Logan returned to Cairo, having left a week earlier after being detained and interrogated by Egyptian forces. “The city was on fire with celebration” over Mr. Mubarak’s exit, she said, comparing it to a Super Bowl party. She and a camera crew traversed Tahrir Square, the epicenter of the celebrations, interviewing Egyptians and posing for photographs with people who wanted to be seen with an American journalist.

“There was a moment that everything went wrong,” she recalled.

As the cameraman, Richard Butler, was swapping out a battery, Egyptian colleagues who were accompanying the camera crew heard men nearby talking about wanting to take Ms. Logan’s pants off. She said: “Our local people with us said, ‘We’ve gotta get out of here.’ That was literally the moment the mob set on me.”

Mr. Butler, Ms. Logan’s producer, Max McClellan, and two locally hired drivers were “helpless,” Mr. Fager said, “because the mob was just so powerful.” A bodyguard who had been hired to accompany the team was able to stay with Ms. Logan for a brief period of time. “For Max to see the bodyguard come out of the pile without her, that was one of the worst parts,” Mr. Fager said. He said Ms. Logan “described how her hand was sore for days after — and the she realized it was from holding on so tight” to the bodyguard’s hand.

They estimated that they were separated from her for about 25 minutes.

“My clothes were torn to pieces,” Ms. Logan said.

She declined to go into more detail about the assault but said: “What really struck me was how merciless they were. They really enjoyed my pain and suffering. It incited them to more violence.”

After being rescued by a group of civilians and Egyptian soldiers, she was swiftly flown back to the United States. “She was quite traumatized, as you can imagine, for a period of time,” Mr. Fager said. Ms. Logan said she decided almost immediately that she would speak out about sexual violence both on behalf of other journalists and on behalf of “millions of voiceless women who are subjected to attacks like this and worse.”

More than a dozen journalists have been detained in Libya in the past two months, including four who were working for The Times. One of the Times journalists, Lynsey Addario, said she was repeatedly groped and harassed by her Libyan captors.