The area around the famous landmark in the United Kingdom capital has been closed off following an incident which occurred on Friday afternoon.
He added: "We heard a noise that I thought was firecrackers going off earlier on".
If reports are to be believed two groups of men are known to have clashed at the spot.
Police then pull a final member of the public off the man and two shots are then heard. "Emergency services attended, including officers from the Met and City of London Police", a Metropolitan Police statement said.
One man was being detained.
A number of vidoes posted to social media appear to indicate that the public may have had a hand in the suspect's capture. "We will release facts when we can-our info must be accurate".
"This is a terrorist incident", Basu told reporters, adding that investigators believe the man was wearing a hoax explosive vest.
In June 2017 eight people were killed and some 48 people were seriously injured when Islamist extremists in a van ploughed into pedestrians on London Bridge before attacking people at random.
Note: This story is developing and will be updated as information becomes available.
Nawaz Sharif was on his way to an appointment at London Bridge Hospital Friday afternoon when the police sealed the area near the hospital because of shooting.
Armed police at the scene of an incident on London Bridge in central London following a police incident, November 29, 2019.
Nurse Jackie Bensfield, 32, described how she asked to be let off a bus on London Bridge after she heard "five or six" gunshots.
"The Metropolitan Police have confirmed that as a precaution the horrendous incident at London Bridge is being treated as though it is terrorism-related".
During the incident on Friday, armed officers burst into restaurants in the Borough Market area at London Bridge and urged diners to leave as fast as possible.
The last civilian then runs out of the way before a police officer fires a shot at the alleged attacker. They later said that enhanced patrols would be implemented throughout the city during this busy shopping period.
At least one person has been killed and multiple people injured in a suspected terror attack around London Bridge.
British Prime Minister Boris Johnson said on Friday he was being kept updated on the incident.
Mike King, a parish councillor at St Magnus-the-Martyr, a church near London Bridge, told BBC News that members of the public were directed into the church by police.
Earlier this month, the British government downgraded the terror threat facing the country from "severe" to "substantial".