People snapping photos and taking videos at accident scenes and publishing them on social media is prompting concern among police.
A yet-to-be identified drone was spotted flying over the scene of a serious car crash just south of Timaru on Wednesday night.
The drone operator may have been breaching Civil Aviation Authority (CAA) rules, but that type of behavior was part of an overall worrying trend, police say.
They have noticed an increase in the number of people taking photos and videos at crime scenes, leading to concerns about privacy and re-victimization.
Senior Sergeant Mark Offen, of Timaru, said the trend was concerning, as members of the public were not constrained by the same rules as media outlets.
"Someone who isn't media trained could, by being naive, breach someone's privacy. They could also cause more distress if it is graphic or inappropriate."
Once images were uploaded to social media, the photographer lost all control over how it was used, he said.
"The advent of mobile phones has changed the way things can be recorded."
The increasing use of drones was also a concern for police, Offen said.
As well as the possibility of capturing footage that was graphic or could breach privacy, there was also the risk of contaminating a scene, he said.
"What would happen if something happened to the drone and it crashed into the middle of our scene?"
Posting photos from crime or crash scenes also ran the risk of informing family members of friends of the death of a loved one before police could.
"The last thing we want is for them to find out on Facebook," Offen said.
There was no good way to break that kind of news to someone, but police could at least offer appropriate support, he said.
A CAA spokesman said civil aviation rules did not allow drone operators to fly at night, unless they were certified to do so by the CAA.
It was unclear if the drone operator at the crash scene near Timaru had that certification.
Civil aviation rules also required unmanned aircraft operators to gain permission from any people they want to fly over, the spokesman said.
"It is unlikely that emergency services would allow this in most instances."
A police spokesman said police were aware of drones being used above crash sites and in other serious incidents.
Police had no issue with people using drones legally, but would be concerned at any activity that could interfere with any response or investigation by emergency services, or would create additional distress for crash victims who may be filmed, as well as their families.
"In cases where people have lost their lives, police would be extremely disappointed if there were to be any footage made public that could identify victims and cause their families further hurt before they have been visited and notified by police."