Republican presidential hopeful Ben Carson has cancelled his scheduled events after four campaign workers were in a collision in western Iowa, leaving three with minor injuries and one dead.

Campaign spokesman Jason Osborne said the crash happened Tuesday morning when the van carrying three volunteers and a paid staffer flipped onto its side on an icy road and was hit by another vehicle.

The Iowa State Patrol was investigating the Cass County crash but didn't have details.

​Three of the staffers were treated at a hospital in Atlantic, Iowa, and released later Tuesday with minor injuries, Osborne said on Twitter.

Osborne said a male volunteer with the worst injuries was taken to a hospital in Omaha, Neb. ​

An official for the hospital later said the Carson campaign volunteer, 25-year-old Braden Joplin, died late Tuesday afternoon.

Joplin was a Student for Carson volunteer, according to Osborne.

Carson, who was in South Carolina, said on Facebook he has suspended his campaign events and spoken with the families of the volunteers.

He also said he plans to fly to Omaha "to be with the family during this difficult time."

In a statement released by his campaign, Carson wrote, "One of the precious few joys of campaigning is the privilege of meeting bright young men and women who are so enthusiastic about their country that they will freely give of their time and energy to work on its behalf. America lost one of those bright young men today."

Rivals offer condolences

Politicians from both sides of the aisle offered prayers and condolences for Joplin and the Carson campaign.

Democratic presidential hopeful Bernie Sanders paid tribute to Joplin in a rally in Iowa City, Iowa.

"I have a lot of respect for any young person who gets involved in the political process," Sanders said. "Our hearts go out to the family of the young man."

Donald Trump mentioned the Joplin`s death in a rally in Ames, Iowa, while many other Republican presidential candidates reached out through social media.