A live audience watched in horror as a man sitting among Leeds fans ran onto the field and shoved the veteran goalkeeper in the face, according to the BBC.
The incident occurred during Friday's Football League Championship (English soccer's second division) game between local rivals Sheffield Wednesday and Leeds United. After visitor Leeds tied the game with a 77th-minute goal, a number of its fans left their seats and and ran toward the edge of the field.
But one of them decided to celebrate between the lines and attack Kirkland. He struck the 31-year-old in the face with both hands, causing him to fall to the ground.
"After conceding the goal, I was looking at the ground but when I looked up, I caught a glimpse of someone coming towards me," Kirkland said. "I thought he was going to give me some abuse but then suddenly he came at me with both hands and I was stunned – you never know what could have been in his hands.
"Later on I thought of my family watching something like that and it was not nice to think my daughter saw me assaulted like that.
"I want the authorities to look at what happened and take the appropriate action because sooner or later, we could be talking about something even more serious."
The attacker then returned to the section where 5,000 Leeds fans were seated, as stewards were unable to apprehend him. Cameras showed an up-close image of the smiling man, who left the stadium without being stopped.
However, fans identified the man on social networks and police sprung to action, according to the Telegraph.
"With the public's assistance we have clearly identified the offender who ran on to the pitch during the match," Senior investigating officer, Detective Inspector Mark Monteiro said. "We are dealing with the complaint made by the player and we are currently taking statements, collating evidence and making inquiries to locate and arrest the offender."
A 21-year-old man was arrested on suspicion of assault Sunday. He remains in custody while police continue their investigation.
Watch the attack on Kirkland in the video below.
Photo via Facebook/Football News