EMBED >More News Videos Philadelphia Capt. Jason Smith speaks to reports on the double stabbing of sisters on August 22, 2019.

EMBED >More News Videos Police: Argument over social media leads to deadly double stabbing. Maggie Kent has more on Action News at 5 p.m. on August 20, 2019.

PHILADELPHIA (WPVI) -- A teenager who remains on the loose has been charged in the double stabbing of two sisters that left one dead, Philadelphia police said Thursday.Nineteen-year-old Tianna Thomas has been charged with murder, attempted murder, aggravated assault and related charges.Police are looking for her whereabouts. They are also searching for seven other females who they said were participants in the assault.Police said Thomas lived across from the sisters in the Brewerytown neighborhood.The stabbing happened around 11:30 p.m. Monday on the 1500 block of North 29 Street.Shawntae Garrison, 23, was found lying on the ground with multiple stab wounds, police said. She was taken to the hospital where she died.Garrison's sister, 28-year-old Tayshawn Layton, was also stabbed multiple times. She was just released from the hospital.Their mother, Arlene Layton, is now begging the suspects to come forward."I ask the people, whoever did this to her, please turn yourself in. It's not going to bring my daughter back but I need justice for her it's not fair," she said.Captain Jason Smith said video captured the assault.It begins with two females being seen leaving 1507 29th Street with Thomas. They were then observed meeting up with five other females at 29th and Jefferson.Smith said they then approached Garrison, Layton, and others, and an altercation ensued.Smith said a suspect, believed to be Thomas, was seen standing over Garrison, repeatedly stabbing her, as the victim was on the ground.Smith said Thomas then stabbed Layton.Early in the investigation, it was believed a social media post might have led to the stabbing incident. However, police said that was never corroborated.Smith said the motive appears to be a neighborhood dispute.The seven other females may potentially be charged with conspiracy and the same offenses as Thomas, Smith said.Smith urged Thomas and the other seven females to turn themselves in. As did the victim's mother, Arlean Layton, "You can't run but so long so please, please please, turn yourself in."