WATCH: Wash. teens arrested after allegedly beating girl, posting video on Facebook

(CBS) SEATAC, Wash. - Two teens are under arrest after allegedly beating up a 13-year-old girl in SeaTac, Washington and then posting video of the assault on Facebook, CBS affiliate KIRO reports. 

PICTURES: Facebook-related crimes

The video shows 14-year-old GlennaLynn Marie Santos and 15-year-old Keanna Beaver hitting Jaden Sanders in the face as she tried to get away.

The beating produced bumps, bruises and a black eye, according to the station.

SeaTac police Sgt. Ted Boe said the victim didn't fight back and was just trying to protect herself.

Boe said Santos posted the video of the attack on Facebook just 17 minutes after it happened on Sunday afternoon. The video was reportedly accompanied by a post from Santos reading, "She thought I was gonna let her go after hitting my brother?"

Police confirmed that Sanders hit Santos' friend's brother earlier in the day but they said the incident did not warrant the revenge-type assault, KIRO reports.

Santos and Beaver turned themselves in to police outside Madrona Elementary School on Monday morning.

"We're doing the time," Beaver told KIRO. "We come up here and we honestly turned ourselves in, and we're willing to do the time for what we did."

Police said Santos and Beaver would spend the night in youth detention after their arrest and they will be charged with assault.