Emergency services have called off a search for a man believed to have jumped into the River Thames from Westminster Bridge, the Metropolitan Police said.

The incident happened as people gathered to hold a vigil to honour the victims of last Wednesday's London terror attack.

Scotland Yard said a response team was called to sighting of the man – reportedly in his mid-twenties – shortly before 11.30am on Wednesday.

Westminster Bridge was closed and London Fire Brigade said they searched the water as far as Lambeth Bridge.

Fire engines, police and rescue boats rushed to the scene after a member of the public reported the incident, but they were unable to locate him.

A Twitter user called Isa who said they were in an office overlooking the incident said: "Watching the scenes at Westminster Bridge atm (at the moment), it's reassuring to see how quickly and meticulously the emergency services have responded."

In a separate incident, at 13.11 on Wednesday, a woman was recovered from the water after falling from the south-east corner of Westminster Bridge.

She is safe and is being treated by London Ambulance Service and will be dealt with under the Mental Health Act, Scotland Yard said.

In pictures: Westminster attack Show all 9 1 /9 In pictures: Westminster attack In pictures: Westminster attack An air ambulance lands after gunfire sounds were heard close to the Palace of Westminster in London PA wire In pictures: Westminster attack MPs wait until the situation is under control in Westminster. 'The alleged assailant was shot by armed police,' David Lidington, leader of the House of Commons, told the house. BBC News In pictures: Westminster attack Crowds gather in Westminster after shooting incident, which police are treating as terror attack BBC News In pictures: Westminster attack Police were also called to an incident on Westminster Bridge nearby AP In pictures: Westminster attack Early reports indicate the car, which mounted the pavement on Westminster Bridge and mowed into around a dozen people, was the same vehicle which then rammed into the railings of the Palace of Westminster, just around the corner Reuters In pictures: Westminster attack Security sources described the suspected assailant as a middle-aged Asian man, who is understood to have left the car before attacking a police officer with a seven-to-eight inch knife PA wire In pictures: Westminster attack Police have asked people to avoid the immediate area to allow emergency services to deal with the ongoing incident AP In pictures: Westminster attack One woman has died and a number of others, including the police officer, have been hurt, according to a junior doctor at St Thomas' Hospital Reuters In pictures: Westminster attack At least three gun shots were heard by those inside Westminster, and proceedings in the House of Commons have been suspended AP

A minute's silence will be held at 2.40pm as part of the memorial marking one week since the Westminster attack. Police officers are set to form a human chain with members of the public.