The offender was black and had shaved hair. It is believed he was wearing a dark hooded top.
Detective Chief Inspector Vince Grey said: "I want to reassure the public that we are doing everything we can to catch this offender.
"Officers will be out in the area today, patrolling, conducting house-to-house enquiries and offering reassurance to residents.
"I urge anyone who saw a person matching this description or saw anyone acting suspiciously to get in touch with police.
"It is also important to reiterate how important it is to make sure your property is as secure as it can be."
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Armed siege around property began just after 4pm this afternoon. A man, reported to be aged 72, is in the building and said to be armed
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