A man armed with a knife has been arrested on suspicion of attempting to murder a police officer.
Metropolitan Police officers used a Taser device on the suspect, in Battersea, south west London, at around 12.30pm today.
The suspect was taken to a south London hospital with minor injuries. A police officer injured in the incident did not require hospital treatment, the Met said.
A force spokesman said: "Police were called to Falcon Road, Battersea, to reports of a man armed with a knife, threatening members of the public.
"Officers attended and the man proceeded to threaten police officers."
Police said the man was apprehended on Este Road, at the junction with Falcon Road, near Clapham Junction rail station.
The spokesman added: "The man has been arrested on suspicion of the attempted murder of a police officer.
"A number of knives were recovered from the scene."
Eyewitness Jenilee Graham said she was unaware there was a situation developing until a woman stopped her and told her to get away.
The 23-year-old City worker, from south London, said: "I was coming back from Asda with my mum when we saw a woman who told us to stop where we were going.
"We didn't know what was happening, but then we saw the man who the woman was talking about pop out from behind a bus.
"He ran towards us, then he darted down a side street. It was obviously pretty scary."
She said the suspect was in his mid-20s and was wearing a black jumper, with dark hair and a beard.
The alarm was raised when firefighters based nearby heard shouting in the street and a couple went out to investigate, where they were confronted and threatened by the man, police said.
Officers said the suspect, 26, remained hostile and struck the window of one of the first police cars at the scene.
Terrified passers-by sought cover in a grocery shop as police tried to contain the armed suspect using a Taser.
Servet Kaplan, 22, a store manager at Battersea Food & Wine, said "People were trying to get into my store. There were so many they wouldn't fit through the door. I saw the police Taser the man and it didn't affect him at all, he just carried on running."
Bhavesh Patel, 32, who works at Niki convenience store, said: "I was in the shop at the time and saw everything happen just outside the shop. Police took about 20 minutes to catch him."
Newsagent Ali Moshin, 28, said: "I was scared and I told my colleague we should lock up the shop. We kept the shop locked for about 20 minutes until a policeman came and told us they had arrested the man."
Chief Superintendant Paul McGregor said: "Upwards of 20 police officers arrived on the scene within minutes of the initial call. There were a considerable amount of people around. The incident bought the place to a standstill.
"The suspect attempted to attack a fire station and fire officers. We do not know about the damage to the fire station at this stage. The suspect was attacking vehicles with knives. We contained him by use of vehicles, boxing in his access."
He added: "This is a really good example of how important an effective Taser use can be, in the right circumstances. People would have been seriously injured otherwise. It was very frightening for people locally."
Inquiries are continuing.