Dallas shooting: Police agencies across US on guard amid heightened threats

Threats ranging from generic promises of violence to specific video postings have been doing the rounds on social media

Police agencies across the US are on edge and on guard after receiving threats and calls for violence against them on social media in the aftermath of the killings of two black men and the sniper attack that left five officers dead in Dallas.

Some departments ordered officers to pair up or more generally said they were heightening security.

Authorities have said the Dallas gunman, who also wounded seven other officers and two civilians, wanted to "exterminate" whites in the aftermath of the killings of Philando Castile in Minnesota and Alton Sterling in Louisiana.

The man who killed one person and wounded three others including an officer in Tennessee apparently told investigators he was motivated by the recent killings of black men by police.

Since then, threats ranging from generic promises of violence to specific video postings have been made, only heightening fears of further attacks. In Dallas, authorities received an anonymous threat Saturday, prompting police to tighten up security. Officers swarmed the department's headquarters, searching for a reported suspicious person in a garage before finally issuing an all-clear.

While some threats have been unspecific and not credible, other promises of violence have been more targeted. In Louisiana, a man was accused of posting a video online showing him in his vehicle behind a police car, saying he wanted to shoot and kill an officer.

Police say Kemonte Gilmore flashes a handgun in the video and talks about the slayings of Castile and Sterling.

Police also say a Wisconsin man posted calls on social media for black men to gun down white officers, and a woman in Illinois is accused of threatening in an online video to shoot and kill any officer who pulled her over.

In Mississippi, Waveland Police Chief David Allen was responding to threats of gunfire attacks that were phoned in and announced on social media.

"No problems have yet materialised, thank heavens," Waveland Police Chief David Allen said in an email last night to The Associated Press.

"While we haven't made any arrests, we are running down numerous leads given to us by the public. We been supplementing our shifts with more people and going to calls in groups. The outpouring of offers for help and shows of support from the public has really energised my entire department. At least in my area, police-public relations are strong and healthy," he said.