A man arrested on suspicion of attempted murder after an incident at Tulse Hill station in south London has been detained under the Mental Health Act.

Officers from British Transport Police and the Metropolitan police were called to the station on Monday evening after reports of a man in possession of a knife. Met officers discharged a Taser electronic weapon as they detained the 59-year-old suspect on a platform shortly after 6.30pm, British Transport police (BTP) said.

On Tuesday, BTP said the man, from Croydon, who was initially arrested for possession of an offensive weapon, had been sectioned under section 2 of the Mental Health Act “following consultation and an assessment with specialist medical staff”.

A witness to the arrest, Conor Fortune, 39, from south-west London, said he was on a Thameslink train travelling away from central London at Tulse Hill station when he heard a male voice “shouting quite loudly”.

He told the Press Association the train conductor then told passengers not to get off because there was a dangerous man on the platform. “After several minutesthe driver announced that we were being held and she shut the doors as a precaution, and advised nobody to get off. She informed us the police had been alerted and were responding,” Fortune said.

Photographs posted on social media showed several police officers surrounding a man who appeared to be lying on the floor.

Play Video 0:31 Police use stun gun on man carrying knife at Tulse Hill station – video

The most recent figures for England and Wales show 750 uses of stun guns in the year ending March 2018 led to detention under the Mental Health Act. After the publication of the figures, Oliver Feeley-Sprague, Amnesty UK’s police and security programme director, said the charity was “particularly concerned at the alarming rise in overuse [of Tasers] against vulnerable and minority groups, including on people with mental health issues.”

People with mental health problems accounted for 18% of the total number of incidents where stun guns or AEPs – attenuating energy projectiles, which are soft-nosed impact projectiles fired from a single-shot launcher – were used.

Robin Smith, an assistant chief constable with BTP, said of Monday’s incident: “This would have been a particularly frightening incident for those passengers at the station or onboard trains at Tulse Hill station. I am especially grateful to our Metropolitan police colleagues who did a great job in detaining this man.”