The San Diego Harbor Police Department is responsible for the safety and law enforcement of tidelands, extending through the five member cities of San Diego, National City, Chula Vista, Imperial Beach, and Coronado. To provide this service, the Harbor Police patrol all five cities in marked patrol vehicles. These vehicle patrols are responsible for enforcing laws, providing general public assistance, and ensuring the security and safety of people visiting San Diego and the tenants who conduct business on Port District property. The San Diego Harbor Police also respond to "calls for service," ranging from welfare checks and burglary alarms to domestic violence and robbery incidents.