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.

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

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."