Authorities in Marin County broke up Halloween weekend gatherings of hundreds of juveniles, the Central Marin Police Authority said Sunday.

On Friday, several large gatherings involving dozens of juveniles took place in Larkspur, San Anselmo and Corte Madera, police said.

Alcohol was present at some locations, and one intoxicated juvenile was released to her parents; another juvenile required medical evaluation, the department said.

One “Social Host Ordinance” citation was issued in Larkspur, which is when an adult or homeowner knowingly allows a party to take place involving alcohol and minors.

On Saturday, Halloween night, more party and noise complaints came in regarding gatherings in Corte Madera and San Anselmo. A large number of teens were dispersed after they entered San Anselmo after a gathering in a neighboring jurisdiction.

Police said parents “took proactive steps” to prevent underage drinking before the parties escalated.

“Central Marin Police Authority appreciates the cooperation of parents and homeowners who worked with officers to address gatherings before they became larger public safety concerns,” the department said.

Katy St. Clair got her start in journalism by working in the classifieds department at the East Bay Express during the height of alt weeklies, then sweet talked her way into becoming staff writer, submissions editor, and music editor. She has been a columnist in the East Bay Express, SF Weekly, and the San Francisco Examiner. Starting in 2015, she begrudgingly scaled the inverted pyramid at dailies such as the Vallejo Times-Herald, The Vacaville Reporter, and the Daily Republic. She has her own independent news site and blog that covers the delightfully dysfunctional town of Vallejo, California, where she also collaborates with the investigative team at Open Vallejo. A passionate advocate for people with developmental disabilities, she serves on both the Board of the Arc of Solano and the Arc of California. She lives in Vallejo.