Officers opened fire in west London on Saturday morning while responding to reports of a car collision, the Metropolitan Police has said.
The Ukrainian embassy said its ambassador’s car was “deliberately rammed” as it sat parked outside the embassy in Holland Park.
When officers arrived on the scene, a vehicle was “driven at them”, the Met added.
Officers used firearms and a Taser before arresting a man in his 40s.
Police said the uninjured man was “taken to a central London hospital as a precaution”.
They added that the situation was neither ongoing nor being treated as terror-related.
A woman who works at a nearby shop told the Press Association she heard shots fired twice between 10:00 GMT and 11:00 on Saturday.
The woman, who did not wish to be named, said officers arrived “very quick”, adding: “I saw many police cars coming.”