Residents from the southern Indian city of Chennai (Madras) are using social media to help those stranded in floods.
Hundreds have taken to social media platforms to co-ordinate search, rescue and food distribution efforts and also reach out to people who need help.
Others have opened their houses to provide shelter to people who cannot reach their homes.
The rains have suspended flights and trains and hundreds of people in the city are without power.
Pushparaj Britto told the BBC that he tweeted about welcoming flood-affected people in his house after seeing similar posts on social media.
"If we can't offer help in this hour of crisis, then what's the worth of human life? I am feeling helpless that I can't go to the affected areas because the roads are submerged. The least I can do is to open my house to people," he said.
Naveen Kumar is hosting three people in his house and says he has space to accommodate two more.
"So many people are affected and they don't have food or a place to stay. We have to help each other. If you do your bit, others will follow you," he told the BBC.
Amba Salelkar has also opened her house to anyone who needs shelter.
"I have lived in Mumbai and have seen terror attacks and flooding. In these scenarios, people need shelter and food. I am a single woman and could have been stranded anywhere. This thought prompted me to offer help," she said.
A temporary website Chennairains.org has also been set up to co-ordinate offers of shelter and food.
The website has asked people who are willing to offer their house as temporary shelters to add their names onto a public document, which is being shared widely.
Others like popular south Indian actor Siddharth are co-ordinating the distribution of food.
People from other parts of the country are offering mobile phone top-ups (recharge) to flood-affected residents.
Several people, including actor Anil Kapoor, have praised the "brave folks" of the city.