A flurry of umbrellas popped up over Potters Field Park, a grassy knoll wedged between City Hall and the iconic Tower Bridge, as many laid flowers honoring the victims.
Before the downpour, Mayor Sadiq Khan led a minute's silence.
"I want to send a clear message to the sick and evil extremists who commit these hideous crimes: We will defeat you. You will not win," Khan said.
A hush descended over the crowd -- couples holding hands, young families, teenagers in tattered jeans, pensioners holding bouquets, and a Muslim group that had traveled by train from their mosque in north London to be at the vigil.
Here are some of their voices:
Hannah, wrapped in her friend's arms, wiped away tears as the rain poured down.
"The attack was a little too close to home," she said after placing flowers in the growing pile.
Her brother-in-law was working at the Wheatsheaf in Borough Market when attackers wielding knives stormed the pub. He was stabbed twice, once in his back and once in his hip. Hannah asked that her last name not be used to protect her family's privacy.
"He was released from hospital today. He's the amazing guy that was able to get everyone into the pub," Hannah said through quiet sobs. "He's our little hero."
"The doctors and police have been so incredible we wanted to come out and show support for them."
A security servicewoman standing nearby walked over to hand Hannah a tissue.
"Our family is feeling very thankful. Many others weren't as lucky as him," she added.
Truus Nayman, an 80-year-old Netherlands native, was standing in a long line of people waiting to place bouquets.
"My husband was Jewish and all of his family died because of anti-Semitism," Nayman, who has lived in London since 1958, said. "I don't want to see that type of hatred take hold here."
"Whatever our differences, we must always come together."
"We laugh when we're happy, we cry when we're sad. We're all the same," she added.
Abduttayyeb Hassanali, 26, was among dozens from Britain's Dawoodi Bohra community, a Shia Muslim sect, attending the vigil. They had traveled from their mosque in Northolt, about an hour northwest of central London.
"I'm a British Muslim and I've lived in London my whole life. I wanted to come and show my support and pay my respects. To commemorate in any way I can," Hassanali said.
Many from his mosque -- women in colorful headscarves and men in golden caps -- carried signs that read: "You are in our hearts and prayers."
"London houses people from all walks of life, all colors, all backgrounds, that's what's great about this city," Hassanali added.
Tom Thornton-Smith, 23, whose office is in the Gherkin skyscraper, was among commuters streaming across the newly reopened London Bridge this morning.
"People were a lot quieter in the office today. Their minds were elsewhere," said Thornton-Smith (in jacket, above). "My mind was in shambles...thoughts everywhere."
He left early to collect his thoughts and found himself at the vigil.
"I'm a very patriotic British person," Thornton-Smith said. "You need to show support after something like this...with all races, all faces, to fight off the evil in the world."
Fola Dawodu, 51, said that Saturday was one of the worst nights of her life.
"My son told me he was going to be out in London Bridge watching football. We were calling him from 11 p.m. until 5:54 when we got a hold of him. I was physically sick," Dawodu said.
He had gone home early and was in bed asleep as his mother frantically tried phoning him.
"I felt I had to come today, to show my support. Not everyone was as lucky as me."
Dawodu, who comes from a Muslim background, says that she's wary of how attacks like this color people's perception of her faith.
"I still go to the mosque, I still pray, but I worry how it reflects on Muslims in our community. It's creating a bad name for us," she added.
Eliza Holmes, Jess Tunks, Lauren Mayes
"As Londoners, people who have grown up here, we felt it was important to come tonight," Lauren Mayes, a 15-year-old from Bethnal Green in east London, said.
"I take a train every weekend to my dad's place that goes through London Bridge. I just keep thinking, it could have been me," she said, looking at her friends.
The teenagers said that their parents were initially worried about letting them attend the crowded vigil, but were ultimately persuaded by their daughters.
"My mum was a bit scared about us coming, but you can't let these things stop you," Eliza Holmes, 15, said.
Meg Goulding and James Morrison
As the crowd dispersed, Meg Goulding, 27, and her partner James Morrison, 28, took shelter under a nearby tree along with a handful of others who were lighting candles.
Morrison, who works in a law firm overlooking the Thames, said the attack's proximity hit him hard.
"This is now the state of play, but at some point we need to figure out how on earth to fix this. We can't keep having this happen over and over again," Morrison said.
"There's such a feeling of helplessness when these things happen. We wanted come down here and talk to other people about love and hope. It's really the only thing we can do when others are trying to spread hate," Goulding, who also works in the city as a lawyer, said.
"We thought we would come down here and hug someone," she added, Morrison's arm around her shoulders.
"We've been hugging each other mostly."