A missing 11-year old boy in India was found after someone saw a police Whatsapp alert.
The BBC reports that police in the northern town of Bareilly say they used the instant messaging service to send out the boy’s photo to several mobile phones in the area.
A man travelling on a train, who had received the alert, recognised the boy sitting near him and called the police.
India has more than 900 million mobile users and WhatsApp is hugely popular.
The app, used by more than 400 million people globally every month, was bought by social networking site Facebook recently for $19bn (£12bn).
“We used various ways to publicise the boy’s story. We printed pamphlets and pasted them around Bareilly. We uploaded a digital copy of the poster on WhatsApp and sent it out as a chain message,” senior police officer SP Singh told BBC Hindi’s Tushar Banerjee.
“By chance, the message reached the right person,” he said.
“The message reached Daanish who had boarded the Doon Express train from Moradabad town [90km or 56 miles from Bareilly]. He recognised the boy from his photo,” Mr Singh added.