Police did not name the person of interest. But sources told KTVU that Yahya Muslim, 28, has been implicated in three shoving attacks near 8th and Harrison streets on Jan. 31.
Muslim is already in custody for an unrelated elder abuse case, according to sources.
"This investigation is in its early stages," Oakland police said in a statement. "Investigators are working hard to forward this case to the DA's office for review and charging."
Surveillance video recorded one of the attacks, showing a man in a black hoodie pushing a 91-year-old man to the ground. The suspect allegedly pushed two other people from behind on the same block near 8th and Harrison streets on Jan. 31.
The victims were injured in the shoving incidents, Oakland police said.
The surveillance footage of an elderly man being shoved to the ground generated widespread interest in the case.
Actors Daniel Dae Kim and Daniel Wu put up a $25,000 reward for information leading to an arrest.