Monica Thomas, 74, of Oakland, was booked Saturday at the Martinez Detention Facility on suspicion of assault with a deadly weapon and unlawful use of tear gas.
Police were called around 10:40 a.m. Saturday to the grocery store at 3649 Mount Diablo Blvd.
Investigators determined that an argument had occurred between two people in the parking lot.
During the dispute, a woman allegedly pointed bear spray through the driver’s side window of a vehicle and sprayed the other person.
The spray hit multiple bystanders in the lot.
As she drove away, police said, she sprayed the person a second time before leaving the parking lot.
Eight people were exposed to bear spray—and one was taken to a hospital—after an argument outside a Trader Joe’s in Lafayette, police said.
Paramedics arrived to treat the victims.
Crews from the Contra Costa County Fire Protection District treated the victims at the scene, and paramedics transported one person to a hospital.
The driver fled before officers could arrive.
Witnesses gave officers her license plate, helping Orinda police spot her car. They pulled her over and detained her on westbound Highway 24.
Police in Orinda found the vehicle traveling on westbound Highway 24 and detained the driver, later identified as 74-year-old Monica Thomas of Oakland.
Thomas was taken into custody that same day.
Efforts to speak to Thomas were not immediately successful.
Police have not disclosed what the original argument was about.
What the argument was about has not been revealed.
In the viral moment that unfolded on Saturday morning, a parking lot dispute outside the Lafayette Trader Joe’s escalated when one person inside a vehicle allegedly pulled out bear spray during a confrontation with another shopper. During the argument, the woman pointed bear spray out of the driver’s-side window of her vehicle and sprayed the other person. As she drove away, police said, she sprayed the person a second time before leaving the parking lot. The chemical spread to bystanders waiting in the busy parking lot, and emergency crews responded to treat the cascade of victims.
Under California law, civilians may possess tear gas only for self‑defense. Using it for any other purpose is a criminal offense that can be charged as either a misdemeanor or a felony, with potential penalties of up to three years in state prison.
The incident remains under investigation.