A GSU officer stationed at State House Gate D in Nairobi has died after a man armed with a spear launched an unprovoked attack, killing him.

The assailant was quickly subdued and arrested and taken to police custody.

Police say a man claimed to have been sent by Satan to attack the officer.

The motive behind the brazen mid-morning assault remains unclear, though detectives from multiple security agencies are probing whether the suspect had any prior links to the slain officer or if the attack was random. Watch the video.