Protecting our churches and preventing church shootings

Isaac and Keith ask Huascar Rivera (retired State Police Lt. Colonel), in light of recent church shootings as well as other mass shootings, what is your opinion/feeling on people carrying concealed weapons for sake of protection, even to church? What advice do you have for churches to do what they can to prevent a mass shooting at their church? What do you think about security cameras and/or security systems put up on church property? Are Christians not trusting the Lord in making such decisions? How important is it for churches to foster a good relationship and communication with Police in their community? Any advice for pastors desiring to reach out to law enforcement?