A cyclist riding around a residential street in Sheffield while waving a gun was arrested after officers chased him in a car and knocked him off his bike.
It is understood a police BMW knocked the suspect off his BMX after he failed to stop when officers asked him to.
Police tape was erected around the vehicle and a crushed bike could be seen under a rear wheel.
Eyewitnesses said around 50 officers were at the scene at the height of the incident in Abbeydale Road, Sheffield, on Tuesday.
One woman who works in the area said: “I heard a loud screech and I saw officers with Taser guns. I then saw a man shouting ‘its not mine, its not mine’ and about 50 police officers seemed to rush over towards him.
“I have seen everything here - armed police, vans, detectives.”
Karl Lang, who spotted the police activity on his way home from work, said: “There was a police car inside the cordon with a bike underneath.
“There were a lot of police in the area. I must have seen three or four vehicles at the scene and what looked like a team of detectives.
“People were saying somebody had been arrested and there were rumours of a gun.”
A man has been arrested on suspicion of possession of a firearm, South Yorkshire Police has confirmed.
The force released a statement which said: “Officers on patrol in the Abbeydale Road area were stopped by a member of the public shortly before 2pm after seeing a man acting suspiciously.
“Officers attempted to speak to the man seen acting suspiciously, who was riding a pedal cycle.
“The man did not stop for officers and during the incident was knocked off his pedal cycle and was injured.
“The 30-year-old man was arrested on suspicion of possession of a firearm.
“He has been taken to hospital, his injuries are not life threatening.
“Enquiries are ongoing and officers remain at the scene.”