Legal analysis: in an emergency, the police only need to show their police cards to arrest people. When detaining or arresting, a detention certificate or an arrest warrant shall be presented. However, under special circumstances, it can be summoned orally without written formalities (summons card or detention card). You can go through the relevant formalities afterwards.

Legal basis: Article 125 of the Procedures for Handling Criminal Cases by Public Security Organs. When detaining a criminal suspect, the Complaint Detention Report shall be filled in, and a detention permit shall be made with the approval of the person in charge of the public security organ at or above the county level. When carrying out detention, you must show your detention certificate, and order the detainee to sign the detention certificate and press his fingerprint. If the detainee refuses to sign or fingerprint, the investigator should indicate it. In case of emergency, if one of the circumstances listed in Article 124 of these Provisions is met, the criminal suspect may be verbally summoned to the public security organ for immediate examination and legal procedures upon production of the people's police card.