A van transporting the group “hit a patch of ice and flipped on its side where it was struck by another vehicle,” Carson’s campaign said in a statement.
A volunteer named as Braden Joplin, 25, died, while three others including a campaign staffer who was driving the vehicle were checked and later released from a hospital.
“I’m suspending all campaign activities today due to a car accident involving members of our team,” Carson said on Twitter.
His campaign said Carson was to travel from South Carolina to Omaha to meet the dead volunteer’s family and will later make a statement.
Rivals Marco Rubio, Ted Cruz and Rick Santorum all tweeted their support for Carson’s campaign team after the accident.
Carson, a retired neurosurgeon, is among 12 candidates seeking the Republican presidential nomination in 2016.
Many of them are barnstorming Iowa in harsh winter weather as they seek to secure support in the run-up to the February 1 Iowa caucuses, the first votes in the presidential nomination process.
Carson is running fourth in Iowa, according to a poll average compiled by RealClearPolitics.com.