Ms. Felgenhauer was in critical condition in a Moscow hospital but her life was not at risk, the radio station reported. It said the assailant, a short man in his 40s, “saw Tatyana Felgenhauer and threw himself at her” without explanation.
Police questioned the man but did not comment on possible motives.
The attack immediately touched off social media posts suggesting a political motivation, though other possibilities were also discussed.
Two Russian news agencies, Interfax and RIA Novosti, cited unidentified police sources suggesting an unspecified “personal” motivation behind the attack. “The main version now is hooliganism,” Interfax reported. Other Russian news media, citing online posts possibly written by the attacker, said the man was deranged and may have become fixated on Ms. Felgenhauer for sexual reasons.
Still, the attack took place amid escalating pressure on the station. One commentator, Yulia Latynina, recently left Russia after unidentified assailants splattered her with feces as she walked on a sidewalk.
This month, Russian state television singled out Ms. Felgenhauer in a report critical of what it called Echo of Moscow’s role “attempting to form pro-Western positions” in Russian society. “The selection of experts and the layout of informational and political material speaks for itself,” the state TV report said.
That broadcast on Oct. 11, called “Echo of the State Department,” said the station collaborated with foreign-funded nongovernmental organizations and was “carrying out anti-government policies, in essence.”
In Russia, such politically hued screeds on state television often set the tone for future action by prosecutors or proxy organizations, although there was no indication that the assailant who attacked Ms. Felgenhauer belonged to any such group.