Does the traffic police have the right to close the road to the gas station?

It should be possible. If there is an accident near the gas station, the road can be closed. According to Article 16 of "Traffic Police Law Enforcement Norms on Road Duty", if the traffic police have the right to block the road sections with accidents or traffic jams, they are temporarily not allowed to pass. The traffic police are diverting traffic. In case of emergency, they can take corresponding compulsory measures against the accident section, so they should have this right.

Article 16 The traffic police should use standard terms when carrying out traffic control, carrying out traffic security tasks and maintaining traffic order at the scene of traffic accidents: Traffic control is being carried out ahead, please wait patiently.