Republican presidential candidate Ben Carson cancelled campaign events for 19 and 20 January after a 25-year-old student volunteer was killed in a car accident in Iowa. The volunteer, identified as Braden Joplin, was flown to Nebraska Medical Center's trauma centre, where he later died.

"Braden Joplin died following an auto accident on slick roads near Atlantic, Iowa," a campaign statement said. "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."

According to Politico, the two other volunteers and the staffer were taken to Cass County Memorial Hospital in Atlantic, Iowa. The incident occurred when the van the four were riding in hit a patch of ice, flipped on its side and was hit by another car.

Iowa State Police Sargent Nathan Ludwig told CNN the accident happened on 1-80 near Atlantic around 9.45am local time after the drive lost control of the vehicle while attempting to switch lanes. The van drove through the median and was struck by a Chevrolet Avalanche pickup truck.

"Dr Carson is asking people to join him in prayer for all the individuals and families involved," campaign spokesman Larry Ross told Politico. Ross said no additional details were available yet. "We are following [Carson's] lead and only sharing information we know to be true, and will provide additional details as available and appropriate."

In the statement, Carson asked people to join him in prayer for those injured in the crash.

Several campaigns shared their sympathies for Joplin's death. Ted Cruz retweeted CNN's Jake Tapper's tweet of condolence, while Donald Trump's campaign manager tweeted: "Thoughts & prayers with @RealBenCarson's volunteers & staff- involved in a car accident this morning." On the Democrats side, Martin O'Malley's Iowa team tweeted their condolences to Joplin's family and the Carson campaign.