The two suspects who remained at large after six teen girls beat a mentally ill woman “for fun” in Chester, Pennsylvania this week and posted video of the attack on Facebook were arrested on Friday afternoon.

The girls who were arrested first – between the ages of 15 and 17 – face assault charges and will likely be prosecuted as adults, The Associated Press reported. They are now being held on $50,000 bail for the attack.

Of the remaining two, one is a juvenile and the other is 19, said the AP.

When asked what motivated the attack, police detective James Nolan said there doesn’t seem to be any reason.

“It appears just for fun,” Nolan told the AP. “There hasn’t been a discernible explanation as to why.”

A local mother saw the video online and alerted police.

As news of the attack spread, a father turned in his 16-year-old daughter late Thursday.

In the video, the cellphone camera captures the girls approaching the 48-year-old victim as she sat outside her home Tuesday night.

You can hear the girls planning the attack and asking who will record the events.

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They swarm the woman, taking turns beating her before forcing her inside her small, ground-floor apartment.

“Their behavior is animalistic to this poor woman,” Delaware County District Attorney Jack Whelan told the Delco Times.

“We are going to aggressively prosecute each of them for their callous indifference to this woman.”

The AP noted that the first four have been charged as adults with aggravated assault, reckless endangerment, burglary and harassment.

The victim didn’t call police, but did seek medical attention at a local clinic, NBC Philadelphia said.

She sustained cuts and bruises, but no broken bones.

View more videos at: http://nbcphiladelphia.com.

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