I'm not sure if it's being reported anywhere as yet re the persons nationality etc. I always think it's prudent to wait for more info e.g. look at the guy who attempted to kill Trump. No doubt before his nationality was known folk would have been saying 'it'll be one of those illegals!'
What's ironic in a way is, if the person does fall into the 'foreign/migrant' bracket, jeez will we hear a lot from Reform etc. However if it transpires the person is a white born and bred Brit, then we might not hear quite as much from them