Former presidential candidate Ron Paul is taking heat for a tweet he sent out Monday afternoon about the Navy SEAL who was killed at a Texas gun range over the weekend.

Chris Kyle, 38, a decorated Iraq war veteran, a former SEAL and author of “American Sniper,” was shot and killed Saturday. Police arrested Eddie Ray Routh, 25, a veteran authorities say may have a mental illness related to his military service.

In response to the news, Paul tweeted: “Chris Kyle’s death seems to confirm that ‘he who lives by the sword dies by the sword.’ Treating PTSD at a firing range doesn’t make sense.”

The tweet set off a chain reaction of criticism online.

Aaron Worthing (@AaronWorthing) responded: “What the Hell, @RonPaul? Are you actually blaming Chris Kyle for his own death?”

More On This... Former Navy SEAL Chris Kyle fatally shot at Texas shooting range

Michelle Lancaster (@SkiGarmisch) added, “Very disrespectful commentary to this man, his memory and his family. Shame on you.”

Razor (@hale.razor) wrote, “So all veterans, once done serving our nation with honor, deserve to be murdered as civilians? Wow.”

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Calls and emails to Paul for comment were not immediately returned. He averages about two tweets a day, typically about policy issues ranging from immigration to the Federal Reserve. Paul, who is known for his anti-war views, retired as a long-time Texas congressman earlier this year.

Kyle, the most lethal sniper in the U.S., had 160 confirmed kills. He enlisted in the Navy in February 1999 and was discharged in November 2009. He had four tours in Iraq under his belt and received 14 different awards and decorations, including two Silver Stars, five Bronze Stars with Valor and two Navy and Marine Corps Achievement Medals. After leaving the Navy, he wrote his biography, “American Sniper.”

Last year, Kyle told the Fort Worth Star-Telegram that he didn’t go into the service for the money or awards.

“I did it because I felt like it was something that needed to be done and it was honorable,” Kyle said. “I loved the guys.”

Routh, a former corporal in the Marines, is being held on $3 million bond. He is also accused of killing Chad Littlefield, 35, who was at the gun range with Kyle. Routh has been charged with one count of capital murder and two charges of murder. Routh served on active duty from 2006 to 2010. He fought in Iraq in 2007 and was sent to Haiti in 2010.

The Associated Press contributed to this report.