CCTV footage of the crime went viral
Police in the Indian capital, Delhi, have arrested a 20-year-old man for brutally stabbing and murdering a 16-year-old female friend in public.
Footage of the assault shows the man repeatedly stabbing the girl and crushing her head with a huge stone.
The video, which has gone viral and led to outrage in India, shows many people watching the assault or walking by.
Police have romantically linked the couple and say they had quarrelled hours before the murder on Sunday.
The girl was going to attend the birthday party of a friend's son when she was attacked, senior police official Ravi Kumar Singh told news agency ANI.
He identified the accused as Sahil and said he was arrested from near Bulandshahr district in the neighbouring state of Uttar Pradesh.
Mr Singh added that the investigation was going on and that the police couldn't reveal more details at the moment.
After the footage of the gruesome murder went viral, many took to social media to express anger and outrage.
Hashtags such as Delhi murder and Delhi crime were trending on Twitter along with Shahbad Dairy, the name of the locality where the crime occurred.
In a tweet, Delhi Chief Minister Arvind Kejriwal described the murder as "very sad and unfortunate" and said that "criminals have become fearless, there is no fear of the police".
The chairperson of the National Commission for Women Rekha Sharma said the crime showed the "insensitivity" of the people of Delhi.
"There were several people at the spot when the incident took place but no one took any action to help the girl. The case should be heard in a fast-track court and the verdict should come as early as possible," she said.
This is not the first gruesome crime in India where bystanders have been called out for their apathy. In the past too, citizens have been criticised for watching or making videos instead of helping victims of crime.
There was similar outrage and much introspection after the December 2012 gangrape - and the subsequent death - of a 23-year-old physiotherapy student on a bus in Delhi.
Her male companion, who was also assaulted but survived, later recounted how they lay injured and bleeding - but no-one stopped to help them for 25 minutes.