The "P.C. police" are "out in force" in the furor over Donald Trump's comments about Mexican immigrants, fellow Republican presidential candidate Ben Carson says.In an interview with the Daily Caller, the retired pediatric neurosurgeon said critics of the real estate tycoon are less willing to talk about illegal immigration itself."It’s the P.C. police out in force," he tells the Daily Caller. "They want to make very clear that this is a topic you’re not supposed to bring up."Carson's defense came as Trump issued his own statement about the series of corporate defections and condemnations that have followed his June 16 presidential candidacy speech.Carson says "it will be interesting to see what [Trump critics'] reaction is to the shooting in San Francisco" – a sentiment echoed Monday by conservative radio host Rush Limbaugh.Authorities have charged 45-year-old Francisco Sanchez with murder in the shooting death of 32-year-old Kathryn Steinle. The repeat drug offender was released from jail April 15, and though federal immigration authorities had filed a so-called detainer with San Francisco authorities, the city's sanctuary law prevents city workers from cooperating with federal authorities on immigration cases."The guy is an illegal immigrant," Limbaugh said on his daily radio show."He's been deported a bunch of times. Keeps coming back. He's exactly the kind of guy Donald Trump was talking about. Exactly."Carson said the conversation needs to change."What we really need to be talking about is how do we take care of our illegal immigration problem," he tells the Daily Caller. "I’ve talked about that extensively. And the key thing is we have to secure all our borders — north, south, east and west.""And it doesn’t have to be a fence or wall," Carson adds. "That’s stupid. We have all kinds of electronic surveillance devices, drones, not to mention people. So we can do it. And then turn off the spigot that dispenses all the things that they are coming here to get. Then there won’t be any reason for them to do it.""I mean that’s pretty simple, and straightforward," he tells the Daily Caller. "And I think everybody knows that. That’s there’s the ability to do it, there’s not the will to do it. It’s too juicy a political football."