A San Francisco man who ran children’s outreach programs for a nonprofit Marin film institute was arrested on suspicion of possessing child pornography, police said Thursday.

At his home in the city’s Crocker-Amazon neighborhood, 71-year-old John Morrison had multiple devices with “hundreds of child pornography videos and images depicting minors engaged in sexual acts with adults,” according to the San Francisco Police Department.

Morrison, who was arrested on Monday, worked in several programs related to young people, teaching film production and screening classes to children in Marin County and acting as the education director for the California Film Institute, police said.

Officials at the institute said Morrison resigned on Thursday.

“We just learned of these very disturbing allegations today,” Institute founder and Executive Director Mark Fishkin said Thursday.

“We take this issue extremely seriously and are in the process of gathering all the facts related to the matter. Mr. Morrison is no longer an employee at CFI. We have not received any requests for information from law enforcement about this investigation, but if we do we will, of course, cooperate fully.”

Morrison’s involvement in the CFI programs is the subject of an ongoing investigation, police said.

The investigation began in November, when the Police Department Internet Crimes Against Children Unit began a search for the source of graphic child pornography being uploaded and traded through a chat messaging app.

They traced the traffic to Morrison’s residence on Newton Street in San Francisco, according to police.

When detectives executed a warrant on Morrison’s home on Monday, they discovered more than 600 files of child pornography, police said. He has been charged with possession and distribution of child pornography, according to police.

Anyone with more information on this case and potential victims are asked to call the SFPD Special Victims Unit at (415) 558-5500.

Filipa A. Ioannou is a San Francisco Chronicle staff writer. Email: fioannou@sfchronicle.com Twitter: @obioannoukenobi