Google and Facebook are participating in the rescue operations of Chennai flood victims by launching online tools and resources that can help them. With thousands driven from homes and more than 150 reported dead in the floods, relatives and friends are concerned for the safety of their loved ones. At this time of fright, when communications are unreliable, Facebook's Safety Check tool can come in handy.

Facebook users can mark themselves 'safe' using the Safety Check tool, and the connected family and friends on the world's largest social networking site will get notified at once. Facebook's Safety Check tool can also be used to report the status of friends and family who may be in the affected area.

It has been a terrible sight for the past few days in Chennai, which has witnessed the heaviest rainfall in over a century. Besides communications, transportations to and from Tamil Nadu's capital have been affected severely and the city's international airport has been shut down.

To help the victims of Chennai rains, Google has set up a crisis response page, which includes links to emergency helpline numbers, data on relief centers, crowdsourced flood maps, and streets with slow traffic.

Chennai floods have attracted nationwide attention and help has been dispatched from all over the country. Telecom companies, Airtel, Reliance, Vodafone have offered free prepaid credit and mobile data to the residents of Chennai and BSNL has extended the payment of monthly bills, and victims will not be billed for a week.

[Read: Help Chennai: Here's how you can lend a hand to Chennaites; TN flood in images]