Rep. Marsha Blackburn (R-TN) tells Breitbart News in a brief phone interview that America needs to strengthen immigration enforcement to protect our national security.

It has been revealed that alleged shooter, 24-year-old Muhammad Youssef Abdulazeez, immigrated to the United States from Kuwait. On Thursday he opened fire in Chattanooga, killing four U.S. Marines.

“I think that one of the things we have talked about regularly is making certain we know who enters and who exits and that they’re coming on the appropriate visa,” Blackburn said in an exclusive interview with Breitbart News. “That’s going to be important for us to get ICE to tighten that process. We need to protect the sovereignty of our nation and we need to protect the security of our people here in the country.”

Concerns about Muslim immigration to the United States have been ramping up in recent years, with leaders ranging from now former House Intelligence Committee chairman former Rep. Pete Hoekstra (R-MI) to former Rep. Allen West (R-FL) to Louisiana Gov. Bobby Jindal and more questioning why the United States is letting so many people from predominantly Muslim countries into the country without assimilating them into American culture.

“It’s interesting to me that the number one issue when you look at polling?” Blackburn told Breitbart News.

What’s the top area of concern, what’s the top issue? National security. That is what people think about night. Are my children going to be safe? Am I going to be safe when I’m out and about in the community? This is one of the top areas of concern and I think this just puts more focus on that concern and so what we will do is continue to work through the legislative and appropriations processes to tighten all these rules and regulations that ICE and other agencies and making certain that the resources are there that are necessary to protect Americans.

A recent report from the Center for Immigration Studies (CIS) found that 2.5 million people born in predominantly Muslim countries have immigrated to the United States—and when that happens, according to 11-time New York Times bestselling author Ann Coulter, they bring their culture with them.

Blackburn is hoping that the FBI investigation into this matter proceeds quickly and she said she expresses deep “sorrow” for the victims and their families.

“My top line reaction first of all is tremendous sorrow for those who have experienced loss of life and their families,” Blackburn said.

It’s absolutely devastating for the community of Chattanooga after they have now experienced what appears to be a terrorist attack, a terrorist attack on U.S. soil. I know there’s tremendous concern being expressed and of course the FBI is investigating. I guess a Tweet went out followed by the attack, and I think some were surprised to see the FBI activated so quickly and with every passing minute it becomes apparent as to why they were called in and why it has been labeled a federal investigation. It’s just a very sad, sad day.

The U.S. attorney investigating the case has now called it an “act of domestic terrorism,,” although President Obama and other top officials have not called it “terrorism” yet.