A group known as the Black Power Political Organization has apparently made a Facebook post claiming responsibility for the massacre in Dallas. The horrific shooting resulted in five officers being murdered and made yesterday the deadliest day for American law-enforcement since September 11, 2001.
In the aftermath of the Dallas shooting, numerous copycat crimes are being reported around the country, including two shootings in Georgia. The post by the BPPO called on other extremists to attack police, and it is possible that the copycat shootings are motivated by them. The Facebook page for the BPPO has since been removed.
UPDATE: According to the most recent reports, the shooter was not affiliated with this or any other extremist groups.