The campaign confirmed Tuesday evening that Joplin died as the result of his injuries.
"Braden Joplin died following an auto accident on slick roads near Atlantic, Iowa," the campaign said in a statement. "Three other passengers in the van were treated and released from a hospital in Atlantic, but Joplin's injuries were severe, and he was brought to Nebraska Medical Center's trauma center in critical condition for treatment."
On Wednesday, Carson reflected on knowing Joplin.
"This young man was just amazing," Carson told Fox News. "I was fortunate enough to get to know him, and he was so incredibly compassionate. He cared about how other people felt. He would really go out of his way to make sure that everybody was feeling OK, and I just think if everybody acted like him, we'd have a lot fewer problems in our country."
Carson also canceled campaign events for Wednesday.
"We unfortunately had some tragedy in our campaign today," Carson told CNN affiliate WCIV
in Charleston, South Carolina, where he had been campaigning. "One of the vans in Iowa, with one of our staffers and three student volunteers, hit a patch of ice, flipped on its side, (and) was hit by another vehicle."
Carson said he would resume campaigning Thursday.
"We are made stronger when we remember who we are fighting for -- for all that have walked before us, their presence still shines, lighting the way forward as we strive to accomplish our mission," he said
Iowa State Police Sgt. Nathan Ludwig told CNN that the accident happened on I-80 near Atlantic around 9:45 a.m. CT when the driver lost control of the van after attempting to change lanes. The van traveled through the median and was broadsided by a Chevrolet Avalanche pickup truck.
The campaign said three of the passengers, including the campaign staffer driving, were examined and released from Cass County Memorial Hospital in Atlantic, Iowa.
Earlier on Tuesday, Carson said he had spoken with a neurosurgeon who was attending to Joplin. Carson also said he had spoken with Joplin's family.
Carson's Iowa state director, Ryan Rhodes, asked for prayers in a Facebook post.
"Today is one of those days where it's about more than politics please pray for Braden a dedicated volunteer who put his heart and soul into this effort. Somehow the words Trust in God mean more now than can be expressed," he wrote.
Rivals offer thoughts, condolences
Several of Carson's GOP rivals offered their support over Twitter.
"Heidi and I are lifting up in prayer the @RealBenCarson staffers injured in a car accident in Iowa. By His stripes, we are healed. Is. 53:5," Texas Sen. Ted Cruz tweeted.
"Thoughts & prayers with @RealBenCarson's volunteers & staff- involved in a car accident this morning," tweeted Corey Lewandowski, Donald Trump's campaign manager.
"Just heard about the serious car accident involving @RealBenCarson staff and volunteers. Please join me in praying for them," Florida Sen. Marco Rubio tweeted.
"Our thoughts and prayers go out to @RealBenCarson, his campaign staff and their volunteers today. Praying for quick recoveries," former Pennsylvania Senator Rick Santorum tweeted.