In the past month, criminals have murdered six police officers in the line of duty. The number might have been eight if not for the actions of two concealed handgun permit holders.

At this rate, police deaths could be way up this year compared to previous years. By this time last year, only one officer had been murdered. While Republican presidential candidates such as Cruz, Rubio and Trump have spoken out forcefully about police shootings, Democrats have been silent.

You’ve probably heard on the news when at least one of these officers has been killed. But you almost certainly haven’t heard about concealed handgun permit holders stepping forward to protect officers.

-- Last month, a drunken man attacked a deputy sheriff near Austin, Texas. As the deputy relates what happened, “I remember thinking ‘stay in the fight. Just keep fighting, keep fighting. Do whatever you can do, just stay alive you need to go home.’” The deputy ended up having his gun taken away from him. Fortunately, a concealed handgun permit holder pointed his gun at the attacker and ordered him to “freeze!” “I’m alive today because of [the permit holder],” said the deputy. “There are no words to explain it. He’s such an outstanding citizen.”

-- On February 5, in Upper Darby, Pa., a police officer tried to break up a fight between two teenagers who had just gotten out of school. Two other students then jumped on the officer. A crowd of 40 to 50 other students had been watching the fight and “all [started to] move in toward the officer.” At that point, a permit holder told everyone to get away from the cop.

As the Upper Darby Police Superintendent Michael Chitwood described it: “He had the gun in his hand, but he didn’t point it at the kids, he just told them to back off. If this guy didn’t come out and come to the aid of the officer, this officer would have had significant problems.” Fortunately, the officer only suffered “significant hand injuries.”

The permit holder kept the mob at bay until other officers arrived. But that wasn’t the end of it. Even one of the responding officers suffered a “major injury to a leg.”

The permit holders’ actions prevented these incidents from becoming national news stories. When there’s no death, there seems to be no news story. And so, we don’t hear about all the cases where defensive gun use has saved lives.

Another permit holder took heroic action just this past week. This Wednesday, in Warren, Mich., a woman was being repeatedly stabbed with a steak knife. She was struck in the neck, back and abdomen. She was rescued by a permit holder -- a valet driver who just happened to be nearby. Unfortunately, rather than hailing the driver as a hero, his employer fired him.

That same day, another permit holder stopped a shooting at a business office in Hamilton, Ala.

A few days before that in New Orleans, a wanted felon with a long rap sheet for violent crimes shot three men at a gas station. Fortunately, one of the victims had a permitted concealed handgun. The felon fled after he had been shot.

Believe it or not, there were a lot more police murders a couple of decades ago. In the five years from 1990 to 1994, an average of 70 officers were killed annually. From 2010 to 2014, that number had fallen to 51 deaths per year. According to research by David Mustard at the University of Georgia, part of that drop occurred because states adopted concealed handgun laws. When states let law-abiding citizens carry concealed handguns, criminals actually become less likely to carry. Deterring criminals from carrying is of benefit both to civilians and to police.

Perhaps it isn’t too surprising that police strongly support concealed carry. According to PoliceOne, a private organization with 450,000 law enforcement members, 91 percent of officers support very lax concealed handgun laws. Essentially, they believe that if someone can legally own a gun, that person should also be able to carry it.

Police officers have very difficult jobs and put their lives on the line every day. What can we do to help make sure that they can come home to their families? One way is to let law-abiding citizens carry guns.

John R. Lott, Jr. is a columnist for FoxNews.com. He is an economist and was formerly chief economist at the United States Sentencing Commission. Lott is also a leading expert on guns and op-eds on that issue are done in conjunction with the Crime Prevention Research Center. He is the author of nine books including "More Guns, Less Crime." His latest book is "The War on Guns: Arming Yourself Against Gun Control Lies (August 1, 2016). Follow him on Twitter@johnrlottjr.