“It lasted about five minutes,” Ms. Rey said, shaken and afraid. “They spoke perfect French, and claimed to be from Al Qaeda.”

Sigolène Vinson, a freelance journalist who had come in that morning to take part in the meeting, said that when the shooting started, she thought she would be killed. Ms. Vinson said in an interview that she dropped to the floor and crawled down the hall to hide behind a partition, but one of the gunmen spotted her and grabbed her by the arm, pointing his gun at her head. Instead of pulling the trigger, though, he told her she would not be killed because she was a woman.

Image Police officers guarded the street next to the office of the satirical newspaper Charlie Hebdo in Paris on Thursday. Credit... Etienne Laurent/European Pressphoto Agency

She disputed a quotation attributed to her and carried on the website of the French radio service RFI stating that the gunman had told her she should convert to Islam, read the Quran and cover herself. Instead, she told The New York Times in an interview, the gunman told her: “Don’t be afraid, calm down, I won’t kill you.” He spoke in a steady voice, she said, with a calm look in his eyes, saying: " ‘You are a woman. But think about what you’re doing. It’s not right.’ ” Then she said he turned to his partner, who was still shooting, and shouted: “We don’t shoot women! We don’t shoot women! We don’t shoot women!”

One woman was among the 12 people killed in the attack on Wednesday: Elsa Cayat, a psychiatrist and psychoanalyst who wrote a column for the paper. The cartoonists Georges Wolinski, Jean Cabut and Bernard Verlhac were also slain.

The French authorities have identified two brothers as the gunmen. The younger, Chérif Kouachi, 32, has been known to the French authorities as a possible terrorist for a decade. He was detained in 2005 as he prepared to leave France for Syria, where he hoped to be trained to fight Americans. He has been living recently with the second suspect, his older brother, Saïd, 34, in the home of a convert to Islam, and has worked as a pizza delivery man or a shop assistant.