A new drone surveillance system can spot when someone in a crowd is acting violently. It uses artificial intelligence and is going to be tested at a university festival in India later this year.

The system assesses the way each person in a crowd is standing via two cameras on the drone . Currently it can recognise punching, stabbing, shooting, kicking and strangling.

However, once the technology goes on sale, whoever buys it will be able to input their own definition of a violent …