The event is part of an effort to renew interest in the viral social media campaign that has raised money to find a cure for Lou Gehrig’s disease. Organizers said the campaign has raised $250 million thus far and led to an additional $1 billion in research funding.

“Our son’s life was one of grace, determination and purpose, that through his resilience, diligence and courage, he created a movement that is still being celebrated today for all those that have been affected by this horrific disease,” said Nancy Frates, the mother of Pete Frates, who helped popularize the challenge along with Pat Quinn. Both were diagnosed with ALS and have since died.

“Even though his human body is no longer with us, his powerful spirit is still being celebrated along with the historic movement,” she said. “You brought results. But as Pete would say, ‘We can have fun today but the job isn’t done. Let’s get back to work tomorrow.’”

Dr. Merit Cudkowicz, the director of the Sean M. Healey & AMG Center for ALS at Mass General Hospital who was also Pete Frates’ doctor, recalled her first meeting with him and how he vowed to raise $1 billion for ALS research. Among the benefits there have been more drugs to treat the disease.

“It’s hard to believe that dumping a bucket of ice over your head was going to change how we think about ALS, but that simple act did more to raise awareness for ALS than any other effort, and it catalyzed amazing research advances,” she told the crowed of several hundred including ALS patients and their families. “It brought so many new scientists to the field all over the world and that’s making the difference today for people living with ALS.”

After the speakers finished, about 75 people, including several families with small children, lined up on the baseball field in front of tiny buckets. All at once, they dumped ice-cold water from tiny buckets onto their heads, a relief to many on the day when temperatures reached into the 90s.

In the stands, Mike Cunningham, 54, of Canton, Massachusetts, was watching the event from his wheelchair.

Diagnosed with ALS last year, he admitted it can sometimes be hard to get out of his house. But he said he wasn’t going to miss Thursday’s event, which gave him a sense of pride, hope, courage and “thankfulness for all the kindness that people show.”

“People are good. People are kind and they step up when people need help,” he said. “It’s easy to forget that with all the news you hear every day. You see it. You feel it, the kindness. Friends, neighbors, strangers that come out and try to help fight this awful disease.”

In 2014, Quinn saw the ice bucket challenge on the social media feed of professional golfer Chris Kennedy, who first dared his wife’s cousin Jeanette Senerchia to take a bucket of ice water, dump it over her head, post a video on social media and ask others to do the same or to make a donation to charity. Senerchia’s husband had ALS.

Quinn and Frates helped popularize the challenge. When the two picked it up, the phenomenon exploded. Thousands of people participated in the viral trend, including celebrities, sports stars and politicians. Online videos were viewed millions of times.

Lou Gehrig’s disease, named after the New York Yankees great who suffered from it — is also known as ALS or motor neuron disease. It is a progressive neurodegenerative disease that leads to paralysis due to the death of motor neurons in the spinal cord and brain. There is no known cure.