Teen arrested in brutal San Mateo County beating

FILE - Handcuffs sitting on a table. (Bernd Wüstneck/picture alliance via Getty Images.)

A 17-year-old boy was arrested after a violent attack in Moss Beach early Monday, authorities said.

The assault occurred around 2:15 a.m. in the 100 block of Barranca Lane, where San Mateo County sheriff’s deputies found an 18-year-old with severe injuries to his face and head.

Investigators said a girl was in her room when an acquaintance jumped through her open window, screaming for help after running from someone, according to the sheriff's office.

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Moments later, the suspect also jumped through the window and attacked the victim with a blunt object, causing significant facial injuries, officials said.

The victim was taken to a hospital for treatment, and the suspect, a 17-year-old boy from San Francisco, was arrested and taken to a juvenile detention center.

Authorities have not disclosed what led to the incident but said the victim and suspect knew each other.