A Rohnert Park woman who was pulled over to the side of Highway 101 before dawn Thursday was arrested on suspicion of drunken driving and endangering her 2-year-old son, who was in the vehicle, CHP officials said.

CHP officers pulled over to assist with a Ford Explorer parked on the northbound highway’s right shoulder at about 3:20 a.m. near Rohnert Park Expressway. Driver Mayra Ponce, 24, told the officers she had been arguing with her passenger, a man slumped over in the passenger seat, CHP Officer Jon Sloat said in a press release. Ponce appeared intoxicated, and officers arrested her after she showed them an open container of beer she had been drinking and failed a sobriety test, Sloat said.

Passenger Edgar Sanchez, 22, of Napa argued with officers over Ponce’s arrest, claimed he could drive and refused to call for a ride for himself and the child, according to Sloat.

Sanchez was arrested on suspicion of public intoxication. The child was released to a family friend.