WALNUT CREEK — Prosecutors charged a Walnut Creek science teacher on Monday with multiple counts of sexual assault of two young children, arranging to meet a child for sex, and possession and distribution of child pornography, the Contra Costa District Attorney’s Office said.

Walnut Creek Intermediate School teacher Michael Bartel was charged with 16 counts, involving multiple sex offenses against a boy and girl under the age of 10. He is in custody at Contra Costa jail in Martinez on $16 million bail and is expected to appear in court Tuesday.

Bartel, 33, of Martinez, was arrested Friday after a week-long investigation by Martinez police who learned he had made been making statements about molesting children to people online, according to prosecutors. Bartel was arrested during a traffic stop at about 1:30 p.m. Friday at Danville Boulevard and Camille Lane in Alamo.

Walnut Creek police searched Bartel’s classroom at Walnut Creek Intermediate on Friday afternoon and notified the school of the arrest. Later that day, investigators also searched Bartel’s home in Martinez.

Prosecutors said there is no evidence linking Bartel to abuse of students from his classroom currently or in the past.

Charging documents show that Bartel is accused of molesting and sexually assaulting the boy between May 2016 and this month, and the girl between July 2015 and this month.

On Nov. 3, Bartel arranged to meet a boy under 14 years old for lewd purposes and went to the arranged meeting place at the arranged time, according to the court documents. In the last month, prosecutors allege he distributed child pornography and on the day of his arrest investigators found him in possession of child pornography.

Letters sent by school district superintendents in Walnut Creek and Martinez districts informed parents Friday of Bartel’s arrest. Bartel was a substitute teacher in the Martinez Unified School District during the 2013-14 school year, and has taught at Walnut Creek Intermediate since 2015.

“It is always of great concern when one of our own is accused and arrested,” Walnut Creek School District Superintendent Marie Morgan wrote in her letter to parents. “Not only do we recognize the breach of trust it implies, but it also heightens the level of concern for student safety that undergirds everything we do.”

According to Morgan, Bartel has been removed from the classroom and placed on administrative leave, pending the outcome of the legal proceedings. Anyone with information relating to the arrest can call the Martinez Police Department at 925-372-3440 or Senior Inspector Darryl Holcombe with the Contra Costa District Attorney’s Office at 925-957-2263.