Maralyn Ramos, 33, was taken into custody Wednesday evening in the area of San Pedro and Agatha streets in downtown, according to a Los Angeles Police Department spokesperson.
The incident occurred at 3:15 p.m. on May 14 at the McDonald's on East Olympic Boulevard.
Video shows Ramos allegedly picking up a 4-year-old boy and trying to get into a parked vehicle. A young girl who was sitting nearby alerted followed the woman outside and alerted other adults.
She fled on foot after being stopped by a witness, police said.