Two teenage girls have been charged after allegedly attacking three people with a steak knife along a SkyTrain route earlier this week.

The 14- and 15-year-old suspects, who can’t be named under the Youth Criminal Justice Act, were arrested Monday night following a series of stabbings in Surrey, New Westminster and Vancouver.

The eldest is charged with assault causing bodily harm, uttering threats, two counts of assault with a weapon, two counts of possession of a weapon dangerous to the public, and five counts of breaching court-ordered conditions relating to a separate criminal case.

She is being held in custody pending her next youth court appearance.

The 14-year-old is facing a single charge of assault, and has been released into the care of her grandmother. She is also facing a charge of robbery in an unrelated case.

The older teen’s Facebook account suggests she was in jail earlier this month, and Transit Police confirmed they have dealt with the same pair a staggering 142 times over the past 15 months.

“When it starts with this many incidents, often that points to a developmental disorder,” said Ray Corrado, an expert in youth violence.

Corrado said random attacks with no apparent motive are unusual, especially among teenaged girls.

“It’s part of their inability to understand the consequences of the violence and aggression.”

Authorities say Monday’s stabbing spree started with an altercation between two youths and two women outside the Surrey Gateway Station at around 11:30 p.m.

One woman suffered stab wounds to the arm and was taken to hospital, where she remained overnight.

Another woman was attacked in New Westminster, and a man was attacked at Joyce Station in Vancouver. He managed to fend off his assailants using a pizza box, but still suffered a small cut to his finger.

Surveillance video from a restaurant shows the two teen suspects appearing calm and casual as they try to buy a slice of pizza moments before the final attack.

Both girls are due to face a youth court judge Thursday.

With a report from CTV British Columbia’s Lisa Rossington