(CNN) The security firm that left a mock pipe bomb inside Manchester United's Old Trafford stadium apologized for its role in the security mishap.

"I am absolutely devastated that a lapse in my working protocols has resulted in many people being disappointed, frightened and inconvenienced. Nothing I can say will rectify that," said Chris Reid, the head of security at Security Search Management Company, in an emailed statement.

The company left behind an eight-inch, lifelike explosive device in the fifth floor of the men's bathroom in the stadium. It had been used during a training session on Wednesday.

The discovery of the lifelike explosive device triggered a mass evacuation and the cancellation of a key soccer game Sunday between Manchester United and AFC Bournemouth.

Shortly before the 3 p.m. kickoff, Manchester United staff alerted police to the suspicious item found in the bathroom.

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