From the New York Times:

Turning #IllRideWithYou Into Real-World Action in Australia

By NOAM COHEN DEC. 15, 2014

Amid the panic at the hostage siege in Sydney that left two captives and the hostage-taker dead early Tuesday, a call for compassion quickly took hold on Twitter.

Sydney residents writing on Twitter under the hashtag #illridewithyou offered to stand in solidarity with Muslims in Australia fearful of repercussions from the attack, which was carried out by an Iranian immigrant in his 50s who carried a black flag with Arabic writing on it. The sentiment took off on social media and was amplified around the world in more than 250,000 posts to Twitter.

Anti-Muslim sentiment has been high in Australia, at least since September, when the government raised the national terrorism public alert to high in light of fears of an attack by Islamic militants. On Monday, during the 16 hours of the siege at a downtown cafe, when the gunman forced hostages to hold up the flag for the news cameras, a Muslim group reported instances of people spitting at women wearing traditional Islamic clothing.

At such a fraught time, a Facebook note from a Sydney resident, Rachael Jacobs, about riding next to a woman on a train whom she believed to be Muslim struck a chord. She “silently removes her hijab,” or veil, Ms. Jacobs said in her post. “I ran after her at the train station. I said ‘put it back on. I’ll walk with u.’ She started to cry and hugged me for about a minute — then walked off alone.”

A Twitter post by Michael James, identified as a radio producer and reporter in Brisbane, Australia, repeated that anecdote, which was then shared online thousands of times. Another Twitter user, Sir Tessa offered to ride her regular bus route with Muslims who contacted her, and quickly came up with the hashtag

Most of the reactions on Twitter have focused on the good will coming out of the violence.