A man suspected of planning a mass shooting was arrested in Texas after authorities intercepted a message that indicated he was "preparing to proceed", the Kerr County Sheriff's Office (KCSO) said in a statement on Sunday.

Coleman Thomas Blevins, 28, made a specific threat to target a local Walmart store, KCSO said in the statement posted on Facebook.

The Sheriff's Office posted an image of evidence apparently collected from Blevins' apartment that showed a rifle with multiple magazines, a flag with Nazi party symbols and the national flag of Saudi Arabia. Books and hand-written documents were also seized by investigators.

The statement did not specify what kind of message had alerted authorities, but after intercepting it KCSO confirmed, with the help of the Federal Bureau of Investigation (FBI), that Blevins had the capability to follow through with the threat.

Blevins was arrested on a warrant for a "Terroristic Threat to Create Public Fear of Serious Bodily Injury," the statement said.

Blevins is currently on active felony probation and is prohibited from possessing firearms. He is booked into the Kerr County Jail where he remains.

The FBI or other federal authorities may seek federal charges in this case, KCSO said.