Stabbing Suspect On Video Pacing Yard Before Taylor Swift Dance Class Knife Attack

New footage shows a UK man pacing in front of a house 20 minutes before Monday's horrific knife attack at a Taylor Swift themed dance class -- a house that was raided by cops after the massacre.

Check out the video obtained by ITV -- a young man in a green hoodie is seen pacing back and forth in the front of a home.

The attack left 3 children dead, 5 other kids in critical condition. Two adults are also in critical condition.

SOUTHPORT STABBING VICTIMS

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A witness reportedly saw the individual arrive by taxi, and did not pay for the ride.

THE MEMORIAL OUTSIDE

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The identity of the alleged attacker, who has been arrested, has not been revealed, although it appears he's a 17-year-old. The suspect was born in Cardiff, Wales and moved to the Southport area in 2013.

Taylor Swift is heartbroken over the tragedy , penning a poignant tribute to the victims and their families on her Instagram Stories Tuesday morning. She told her followers that she was "completely in shock."