MILL CREEK — A teen was arrested Saturday after a video surfaced online of him allegedly assaulting a boy and stealing his scooter.
The boy was younger than 10.
Police also are investigating the teen, 14, for additional and unrelated crimes, Holly Harvey, a spokeswoman with the city of Mill Creek, said Monday.
The assault happened around 6 p.m. at Westfield Park. The small neighborhood park is located near 40th Drive SE and 134th Place SE.
The filmed assault was posted on Instagram, a social media site used to share photos and videos.
Several people saw the video and called police.
The teen was booked into the Denney Juvenile Justice Center.
A day after his arrest, he reportedly posted threats on Instagram. He allegedly said he planned to take the lives of his classmates on his first day of school at Henry M. Jackson High School.
He was expected to start school there in the fall, Harvey said.
The threats caught the attention of Everett Public Schools leaders.
On Sunday night, Jackson High Principal Dave Peters wrote to families assuring them the district was aware of the situation.
“I have received numerous emails and phone calls from concerned people in the Jackson community about a video and threatening social media post that has been circulating this afternoon,” Peters wrote.
He told families that police had intervened and that the school district is “also taking this seriously and will be moving forward with safety as the highest priority.”
A similar message from Gateway Middle School was sent just before 4 p.m. Monday.
The teen also is under investigation for robbery, malicious mischief and disorderly conduct related to an incident Sunday.
In June, the boy was arrested after his mother reported that he assaulted her. She told police her son punched her when she tried to get him to go to school.
He was charged with fourth-degree assault and his trial is scheduled for next week, according to court records.
He also was arrested in March for allegedly assaulting his mother when she took away the iPad she bought him. The family reported that the boy was missing school because he was staying up all night playing video games.
His parents have sought intervention with the juvenile court, filing an At-Risk Youth petition.
Caitlin Tompkins: 425-339-3192; firstname.lastname@example.org.