The man suspected of killing at least 22 people and injuring about two dozen others in a mass shooting in El Paso, Texas, may have written a manifesto claiming the attack was racially motivated and aimed at Hispanic people.

In a press conference Saturday, law enforcement officials said they were exploring whether a four-page manifesto titled The Inconvenient Truth, posted to the extremist online forum 8chan shortly before the shooting, was written by suspect Patrick Crusius, a 21-year-old white man from a town near Dallas.

Crusius allegedly walked into a Walmart in El Paso late Saturday morning and opened fire on shoppers and employees . Security footage of the scene shows a man entering the building and holding a long firearm.

The manifesto describes a mass attack as a response to the Hispanic invasion of Texas.

They are the instigators, not me, it says. I am simply defending my country from cultural and ethnic replacement brought on by an invasion.

The manifesto includes overwhelmingly racist, xenophobic and anti-immigrant rhetoric. HuffPost has reviewed the manifesto but will not provide a link to it.