If there is probable cause, an arrest can be made by a private company. However, in order to legally make an arrest, a security officer must have seen a crime take place. Security personnel is treated like all other private citizens, so their participation in criminal activity is limited.
What are the services of public security?
The general duties of public security organs include administration of the public order, prevention of crimes against the socialist system, prevention of criminal activity endangering public peace, protection of public and private property, maintenance of public peace, and ensuring the smooth advancement of socialist modernization.

Maintaining public order and safety: Public security services are responsible for maintaining public order and safety by preventing criminal activity and responding to emergencies.