Denver officials said they are not aware of any threats made to President Barack Obama's campaign, but are exploring all possibilities as they investigate the shooting at his re-election headquarters.
Right now, no one is in custody and investigators are looking at surveillance video to see if a vehicle can be identified.
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David Davis is hoping to push Brexit withdrawal talks towards discussions on a future trading relationship between the UK and EU.
A fine start to Sunday but rain moves in from the southwest later on.
A second police officer has died after he and a colleague were shot as they scuffled with a suspect in Florida.