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'New security threat' in Dallas Dallas shooting: High alert over 'new security threat'
(35 minutes later)
Dallas police heighten security across city after new threat, two days after officers killed - media reports Dallas police say they have heightened security at their headquarters after receiving an anonymous threat, two days after the deadly shooting in the city.
This breaking news story is being updated and more details will be published shortly. Please refresh the page for the fullest version. SWAT officers were deployed at the main building, in effect placing it under lockdown, local media say.
If you want to receive Breaking News alerts via email, or on a smartphone or tablet via the BBC News App then details on how to do so are available on this help page. You can also follow @BBCBreaking on Twitter to get the latest alerts. On Thursday, five white police officers were shot dead by a black man, Micah Johnson, during a protest rally.
The march was against the killing of black men by police. Two deaths this week have led to nationwide protests.
In a statement, the police said on Saturday: "The Dallas Police Department received an anonymous threat against law enforcement across the city and has taken precautionary measures to heightened security."
An armoured vehicle was moved close to the main HQ in central Dallas and heavily armed officers were seen nearby, according to the Associated Press news agency.
But it added that members of the public were still able to walk about freely around the building.
The police has not commented on the media reports that the HQ was under lockdown.
The shooting happened late on Thursday during the protest march.
Johnson, who was himself killed during the assault, supported black militant groups who encouraged violence against police.
Dallas police chief David Brown said Johnson had told a negotiator that he had wanted to kill white people, especially white police officers, because he was angry about the recent shootings of black men by police.
The attack came after the police killings of Philando Castile in Minnesota and Alton Sterling in Louisiana.