Police opened fire outside Ukraine's embassy in London on Saturday after a vehicle rammed into the ambassador's parked car and then drove at officers called to the scene.
No diplomatic staff were injured in the incident and nor was the suspect, a man in his 40s, but he was taken to hospital as a precaution after being arrested, police said.
The incident, which began at around 08:30 am (0730GMT) and took place in the exclusive Holland Park area, is not being treated as terrorism.
"The official vehicle of the ambassador of Ukraine to the UK was deliberately rammed as it sat parked in front of the embassy of Ukraine's building," a statement from the embassy said.
It said police were called and quickly blocked the suspect vehicle, but the driver hit the ambassador's car again.
"No one of the embassy staff were injured," the embassy said.
London's Metropolitan Police confirmed they were called to reports of a car hitting a number of parked cars near the Ukrainian embassy.
"On arrival at the scene, a vehicle was driven at police officers," the force said in a statement.
"Police firearms and Taser were discharged, the vehicle was stopped and a man, aged in his 40s, was arrested.
"He has been taken to a central London hospital as a precaution. He was not injured."
The statement added: "The incident is not being treated as terrorist-related."
Senior police officer Andy Walker said there would be an investigation into the discharge of a police firearm, as in line with procedure.