Police were called at about 6.45pm on Tuesday, 25 April to reports of a man in possession of a knife outside Tooting Railway Station.
When officers arrived, the man ran towards them with a knife.
Police discharged a Taser as the man was detained. He was subsequently arrested on suspicion of affray and possession of an offensive weapon.
The knife has been recovered.
The man, who is aged in his 50s, was treated for minor injuries. No one else was injured.
He remains in custody at a south London police station.
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