The Acting Deputy Commissioner dismissed as “nonsense” a question from a journalist while making a statement on Friday.
In a last question at the end of Mr Rowley’s statement, the journalist asked: “Why did Mr Craig Mackey leave the scene, why didn’t he stay to help PC Keith Palmer?”
Mr Rowley responded it was “frustrating” to receive such a question when the Met was “wrestling with an issue like this”.
Mark Rowley hit out against the "frustrating" query about Craig Mackey in the London terror attack
It’s frustrating when we’re wrestling with an issue like this
He said: “It’s frustrating when we’re wrestling with an issue like this and the Acting Commissioner’s doing an excellent job that we get nonsense from armchair critics.
“Can we focus please on the investigation and the public appeal.”
London mourns terror attack at vigil Fri, March 24, 2017
The world grieves after an attacker killed three people and injured about 40 near parliament in London.
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Floral tributes are left after the vigil in Trafalgar Square, London to remember those who lost their lives in the Westminster terrorist attack
Police made the arrests overnight in the West Midlands and the North West of England, Mr Rowley, said during this morning's briefing.
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The number of arrests has now risen to ten, with nine still in custody after a woman from Birmingham was released on bail.
He revealed two of the victims of Khalid Masood's attack remain in critical condition in hospital, with one in a life-threatening condition.