Republican presidential candidate Ben Carson on Thursday suggested that concerns about Syrian refugees in the United States are akin to a parent's concerns about "mad dogs."

"If there’s a rabid dog running around in your neighborhood, you’re probably not going to assume something good about that dog, and you’re probably going to put your children out of the way," he said during remarks in Mobile, Alabama. "[It] doesn’t mean that you hate all dogs, by any stretch of the imagination, but you’re putting your intellect into motion and you’re thinking 'How do I protect my children? At the same time, I love dogs and I’m gonna call the humane society and hopefully they can come take this dog away and create a safe environment once again.'"

"We have to have in place screening mechanisms that allow us to determine who the mad dogs are, quite frankly," he added. "Who are the people that want to come in here and hurt us and want to destroy us? Until we know how to do that, just like it would be foolish to put your child out in the neighborhood knowing that that was going on."

Several 2016 presidential candidates and a host of governors nationwide have called for a halt to a program allowing migrants from the war-torn nation into the U.S. amid worries that terrorists could enter the country as refugees.

Carson also said Thursday that ISIS poses a "much greater" threat to the United States than al Qaeda did before 2001 because the September 11 attacks "really didn’t require a great deal of sophistication."

"You had to be able to fly some planes and get a couple of people in here. That’s going to be a lot more difficult now," he said.