A 14-year-old girl who allegedly moved through the corridors of her high school brandishing knives and wounding both staff and students is now facing 15 criminal charges, police said Wednesday.

Durham Regional Police laid the charges 24 hours after the stabbing at Dunbarton High School in Pickering, Ont., which left seven people with non-serious injuries.

The charges include one count of assault, six counts of assault causing bodily harm, seven counts of assault with a weapon and one count of possession of a weapon for a dangerous purpose. 

Police have yet to determine the teen's motive, but posts by the suspect on social media foreshadowed the attacks.

She wrote about suicide attempts and not feeling normal, and last month she posted about the urge to commit a stabbing at her school.

On Tuesday, she posted she was going to follow through with the attack.

John Legere, superintendent of the Durham District School Board, told CBC News the board had been unaware of the posts. 

"We were not really aware of any comments brought forward to the school generally regarding this," he said. "The police are certainly aware of online activity and they're exploring that angle … the school is also becoming aware of some online activity as well, and we will co-operate with the police as part of addressing that in their investigation and the school board's as well."

5 students, 2 staff members injured

​Police said five students and two staff members were hurt in the attack, revising the figures of six students and three staff offered by the Durham District School Board on Tuesday night.

The girl, who cannot be named under the Youth Criminal Justice Act, is facing seven counts of assault with a weapon and six counts of assault causing bodily harm. She is also charged with possessing a dangerous weapon and assault.

She was scheduled to attend a bail hearing on Wednesday morning, the outcome of which was not known.

Dunbarton High was open for classes on Wednesday, 24 hours after chaos reigned in the hallways.

The knife attack, which police say began after 8 a.m., sent students and teachers running for cover. Witnesses described seeing a girl running down school hallways waving a knife in each hand.

One emotional 14-year-old girl said she came face-to-face with the suspect, who slashed at her with the knives.

'I just ran for my life'

"I just ran for my life," the girl said as she began to cry. "I just can't believe it happened. She almost got me."

Another student said the scene hardly seemed real. "People were running and screaming. There was blood on the
ground. I thought it was fake."

Police credited two staff members with thwarting any further attacks by wrestling the girl to the ground and holding her there until officers arrived.

"We're giving kudos to the staff members that stopped this before it got worse," Sgt. Bill Calder said after the incident.
"They did the right thing."

Investigators said in a release they did not believe any particular student or staff member was targeted in the attack.

"She appeared to be acting alone," Calder said.

Dunbarton High tweeted that life appeared to be returning to normal, adding that supports were available to students who may need them.

"Great to see so many students back at school," read a tweet sent Wednesday morning. "Supports are available in guidance for all staff students."

With files from CBC News