SAN PABLO — A San Pablo police officer already on administrative leave was arrested last week by San Francisco police for multiple charges related to a purported drug sale that took place with a two-year-old child sitting in the officer’s car.

Officer Kenneth White, 32, was arrested Wednesday afternoon, according to San Francisco police spokesman Officer Albie Esparza.

Two days before White’s arrest, San Pablo police notified authorities in San Francisco that White may have been involved in illegal activities, San Pablo police Cmdr. Gene Alameda said.

San Francisco officers were monitoring White about 2:30 p.m. Wednesday in the area of Seventh and Howard streets when they observed a man identified as Timothy French, 57, of San Francisco, walk to White’s car, look into the car window and participate in what appeared to be a drug transaction, Esparza said.

Police suspect that White was involved in trafficking heroin and cocaine, Esparza said. A 2-year-old child was in the back seat of White’s vehicle when the transaction took place.

White is being held on suspicion of narcotics violations, weapons violations and child endangerment, Esparza said. It was not immediately clear if he had been charged or arraigned. San Pablo police said they are mounting an internal investigation into the officer’s conduct within the department that Alameda said is unrelated to the arrest. Officials did not say when or why White had been placed on paid leave.

“These are two separate investigations,” Alameda said. “The (internal) investigation by us is still in its process and has to be completed before we take the findings and determine if there is any action to be taken.”

Contact Rick Hurd at 925-945-4789 and follow him at Twitter.com/3rdERH.