Donations to victims pour in from Muslims after the attack in London.

On Wednesday, March 22, 2017, a man sped over pedestrians in his car on London's Westminster Bridge, then slammed his vehicle outside parliament.

The terrorist — reportedly linked to ISIS — stabbed a police officer steps away from Big Ben after leaving his car, before being shot and killed by law enforcement. The officer was one of at least four people, including an American tourist, who died in the attack. About another 40 were injured.

Days like these can rattle any city, as residents grapple to understand unconscionable, senseless acts of violence and terrorism.

But if anyone can "keep calm and carry on," it's Londoners.

"We stand together in the face of those who seek to harm us and our way of life," Sadiq Khan, the city's first Muslim mayor, said in the aftermath. "Londoners will never be cowed by terrorism."

In the hours since the attack, the mayor's comments certainly hold true. Parliament convened business as usual the morning following the attack. Unfazed Londoners went to work, just like any other Thursday. The phrase, "We are not afraid," planted on the underground tube logo, went viral.

One of the more inspiring acts of defiance, however, has been the success of the "Muslims United for London" campaign.

The online fundraiser, aimed at supporting the victims and their families with costs related to the events on Wednesday, calls on the British-Muslim community to rally behind those affected.

It's a powerful rebuke to the idea that extremism represents all — or even a significant number of — Muslims.

The campaign's organizer, Muddassar Ahmed, had been been near Parliament while the attacks unfolded. He saw all the chaos outside his window.

Witnessing the devastation firsthand made a big impression on him, he explained on the campaign's fundraising page:

"I reflected on what it means to be a born-and-bred Londoner and found myself proud of how security and medical services responded, how ordinary passers-by offered first aid, and what our Parliament means to me, an institution that is the oldest of its kind in the world and how, regardless of our critiques of government policies or political parties, remains an institution that reflects how the will of the people can be expressed with civility and dignity."

Ahmed's sentiment struck a chord with many other Londoners as well.

Just hours after the campaign launched, Muslims United For London had already raised over 12,000 British pounds ($15,000) from hundreds of supporters.

It even caught the eye of two Muslim members of parliament, Naz Shah and Yasmin Qureshi, who also chose to donate.

“Looking after people is very much part of Islamic philosophy — to help your fellow citizens," Qureshi explained to Middle East Eye.

While the initial fundraising goal has already been met, Ahmed is encouraging more folks to contribute, seeing as the need is high.

"While no amount of money will bring back lives lost or take away from the pain the victims and their families are going through," Ahmed wrote on the campaign page. "We hope to lessen their burden in some way as citizens, Londoners, and human beings."

Learn more and support Muslims United for London.