FBI alerted Texas about gunman before assault

Reports have emerged that the FBI had warned Texas officials several hours before the controversial Prophet Muhammad cartoon contest that a suspected extremist could show up at the event.

This is according to BBC.

However, FBI Director James Comey said the agency had no indication that the Sunday attack was planned.

Comey said the attempted attack highlights the danger of home-grown extremists, who can gain inspiration and expertise from overseas militants via social media.

Elton Simpson and Nadir Soofi had driven into the car park of the Curtis Culwell Center in Garland, venue of a Muhammad Art Exhibit organised by the controversial American Freedom Defense Initiative (AFDI).

A gun fight had ensured in which a security guard was injured before the gun men were both killed.

One of the attackers, Simpson, who had social media ties tothe Islamic State, had alluded to an attack on Twitter.

US authorities have said Simpson had been under surveillance since 2006 and was convicted in 2010 for lying about plans to go to Somalia.

Soofi was Simpson's roommate and had not been previously tied to terrorism.

Citing that there were till other potential Elton Simpsons out there, Comey said,

"The siren song sits in the pockets, on the mobile phones, of the people who are followers on Twitter. It's almost as if there's a devil sitting on the shoulder, saying, `Kill! Kill! Kill! Kill!' all day long."