Detective Mike Fesperman said the woman might not face criminal charges, the Los Angeles Times reported. He said a "mob mentality" took over at the store Thanksgiving evening as the 10 p.m. opening time approached.
About 20 shoppers were hit by the pepper spray. Fesperman said police have reviewed security tapes from the store and talked to 10 witnesses, with 14 more to go.
The woman's identity has not been released. She came to police voluntarily.
Alejandra Seminario of Sylmar, a Los Angeles suburb, told the Times she was at the store that night and shoppers began tearing plastic off electronic game consoles. She said by the time the pepper spray hit, people were screaming and shoving each other.
"I'm not saying it was right. It could have been a situation that she was in fear for her safety, that she would be crushed," Fesperman said. "It comes down to whether it was a matter of self-preservation or she was trying to gain access to the games."