The US Capitol police chief has told waiting reporters that they believed there was a child in the car involved in the incident and that he did not have any information on the person driving the car.
He said that multiple scene involved are now secure and said he had no information that the incident was related to terrorism and is anything other than an isolated incident.
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He said people have handed over thousands of pounds in good faith, only to find the advert has nothing to do with Mr Lewis or his company.
The memorial service will be attended by Prince Harry and Meghan Markle.
David Browning admits manslaughter by diminished responsibility but denies murder.