we need to make this point, don't we, about whether or not this is terrorism, whether it has been called terrorism because there's a lot of tension around that, and the media is being dragged into that as well. >> reporter: yeah, indeed, that's right, max. the police are not calling it terrorism yet. they're saying the counterterrorism command is involved but they're clearly keeping options open. they make the point the man they have in custody is in hospital at the moment. they say he will undergo a mental health assessment. they're saying he is the only person involved in the incident. we have heard from other witnesses who say there may have been more than one person in stran. the police are not saying that. the point is the politicians are going a little ahead of the police. theresa may, the prime minister, calling it a potential terrorist attack. the mayor of london, sadiq khan, going further and calling it a horrific terrorist attack. we wait to hear from authorities precisely what the motivation was. there's no doubt here on the street, the people here, this