A pair of social media accounts possibly linked to the Islamic State terror group posted messages referencing Sunday evening's attack on a Texas free speech event moments before it happened. 

The Los Angeles Times reported that a Twitter account bearing the name "Shariah is Light" posted a message with the hashtag "texasattack" at 6:35 p.m. Central Time. The account featured an image of Anwar Awlaki, an American-born cleric killed in 2011 by a drone strike in Yemen.

Moments later, authorities say two men pulled up in a car to the Curtis Culwell Center in the Dallas suburb of Garland, Texas and opened fire. A school security guard was injured in the ankle before police officers shot and killed both suspects. 

The suspects were identified as Elton Simpson and Nadir Soofi, a senior federal law enforcement official told Fox News. The men were roommates.

Authorities have not officially determined whether the shooting was linked to an event, a contest hosted by the New York-based American Freedom Defense Initiative that would award $10,000 for the best cartoon depicting the Muslim prophet Muhammad.

"Shariah is Light" also tweeted a command to follow a second account, titled "AbuHussainAlBritani". That second account posted several messages referencing the shooting in Texas and appearing to link it to the Islamic State, also known as ISIS. 

"The knives have been sharpened, soon we will come to your streets with death and slaughter!" the first message from the account read. 

A second message said "Allahu Akbar!!!!! 2 of our brothers just opened fire at the Prophet Muhammad art exhibition in texas!" 

“Kill Those That Insult The Prophet,” a third message said. 

A final message from the account read, "They Thought They Was Safe In Texas From The Soldiers of The Islamic State." 

Both accounts have been suspended by Twitter.

The Associated Press contributed to this report. 

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