6:25 PM PT -- Beverly Hills PD tells TMZ ... Jaime was actually outside of the car when the man began smashing it, but her friend and 4-year-old son were inside, parked along the curb. We're told the man jumped on the vehicle and then on the rear windshield, causing glass to shatter ... which struck King's child.

Jaime's friend then jumped out of the car to confront the guy, and he threw a can at her. Police say the man vandalized another person's vehicle right before King's.

The suspect -- 47-year-old L.A. man, Paul Francis Floyd -- was arrested for felony child endangerment, felony vandalism, and misdemeanor battery. He's being held on $100k bail.

Jaime King was rattled to the point of tears when a stranger jumped onto her car and smashed her windows in the heart of Beverly Hills.

You can tell from the photos ... the actress was absolutely terrified. According to witnesses, Jaime was in her Mercedes-Benz when the man approached on a skateboard, crawled onto her hood ... and then started banging at her windshield.

He eventually moved to the back of her car, and you can see ... he nearly shattered the rear and front windshields. It's unclear when Jaime got out of the car, but she was not injured.

Police got multiple 911 calls from witnesses who said the man was on a mini-reign of terror even before he got to Jaime's car -- allegedly punching and kicking several other vehicles, and throwing cans at several passersby.