Write an article based on this "Open the door a crack if you have a security door or chain lock. Ask to see their credentials. Look for signs that they aren't who they say they are. Offer to call for help if someone is hurt or their car is broken down. Open the door once you're confident it's safe. Leave immediately if you feel like you're in danger."

Article:
Don't do this unless you have something separating you from the person knocking, as they could forcefully push themselves in once you've unlocked and opened the door. If the person knocking is someone you don't recognize and they're claiming to be a police officer or utility worker, ask them to show you the proper badge or paperwork to prove their identity. Grab their credentials through the crack in your door or examine them closely through the security door to see if they're valid. Be skeptical of wrinkled or dirty uniforms. If someone is claiming to be a police officer, check to see that their police badge isn't a fake and that they have the proper police gear like a hat, radio, and utility belt. If you see anything that looks off, call the company the person claims to be with or contact the police and ask them to verify their identity. Have them wait outside while you make the call and don't open the door. Don't feel pressured to let them inside while you place the call. You can say to the person outside: "I just called for an ambulance/tow truck. They'll be here any minute to help you." If you've determined the person outside has a valid reason for being there, go ahead and open the door. Let them in if they need to come inside, but keep an eye out for any suspicious activity once they're in your home. If you notice something suspicious or your feel uncomfortable at any time after you let someone in your home, leave immediately. Go to your neighbor's house or a safe public place and call the police.