A Fresno woman allegedly assaulted and threatened an employee with a knife at a San Rafael car wash, police said.

The incident happened at about 9:30 a.m. Monday at the business near Bellam Boulevard and Francisco Boulevard East.

The suspect got into an argument with another customer and attacked an employee who tried to intervene, police Sgt. Justin Graham said.

The suspect threatened the worker with the knife, punched her and pinned her to the ground, Graham said. The suspect fled before officers arrived, but witnesses gave police a description of her vehicle and the license plate number.

Police entered the information into the automated license plate reader system. At about 8 p.m., the system alerted police in San Pablo that the vehicle had entered their city, and police detained the suspect.

The driver admitted involvement in the attack at the car wash, Graham said.

Megan Joan Ebert, 27, was booked into the Marin County Jail on suspicion of assault with a deadly weapon and battery. Her bail amount was set at $50,000.

Paramedics from the San Rafael Fire Department treated the injured employee.