Police and emergency vehicles rushed to Regina's Cornwall Centre just after 6 p.m. CST. (CBC)

Four people were injured in a multiple stabbing incident early Tuesday evening at the Cornwall Centre, a downtown shopping mall in Regina, police say. A youth is in custody.

According to police, three people were taken to hospital for treatment. The extent of their injuries was not immediately known. A fourth injured person was treated at the scene.

Police said their preliminary investigation suggests it was a random attack, adding the victims did not know the assailant.

"The suspect randomly attacked people in close proximity," police said in a statement Tuesday night. "There is no indication as to the suspect's motive at this point."

Two police officers happened to be in the mall at the time of the attacks, as part of their routine patrol, and were able to get to the scene right away.

He has a knife. He is hitting people with a knife. - Eyewitness account posted to Facebook

They ordered the youth to drop the knife. He threw the weapon at them and was then subdued and taken into custody without any further incident.

EMS crews arrived within minutes. As well, a portion of the mall, outside a coffee shop, was quickly cordoned off. The mall was later closed.

Police say a young man is in custody following a multiple stabbing at the Cornwall Centre in downtown Regina. (CBC )

The ages of the victims or the person in custody were not immediately known, but all are males.

"The paramedics were all around [one of the victims] and there was a pile of blood under him," Summer Pascal, who was in the mall at the time of the attack, told CBC News. "And he got up and his neck on the side was squirting out. It was gushing. There was blood everywhere."

Social media lit up

Within a few minutes of the incident, which police said took place around 6 p.m. CST, social media networks — including Twitter and Facebook — were rapidly transmitting sketchy information about the incident.

"OMG!!!! Stabbing in the Cornwall centre!!!!!" one posting noted at 6:21 p.m.

Another Regina resident shared her experience on her Facebook page.

"A woman came flying into my store right as we were closing and was yelling, 'He has a knife! He is hitting people with a knife!'" the post said. "I saw a guy standing there just holding his sweatshirt up, facing away from me, and it look like he was wearing a red lanyard. And then I realized it was blood. All down his leg."

The poster said she gave the man some first aid until EMS arrived.