BELLEVUE —  Two runaway horses raced along a Fourth of July parade route in a small Mississippi River town in eastern Iowa on Sunday, trampling children who were in the street picking up candy and injuring 24 people, police said.

The horses became out of control after one rubbed its head against the other, removing that horse's bridle. The horses and the wagon attached to them ran for six blocks, running into children and adults seated and standing along the streets watching the parade in Bellevue, a town of about 2,300 people 25 miles south of Dubuque on the Iowa-Illinois border.

The victims were as young as 2 years old and suffered injuries ranging from multiple fractures to collapsed lungs and bruises and abrasions. Five were in critical condition, and five had severe injuries, according to a statement from the city's police and fire departments.

"The mood is shock and disbelief," Bellevue Mayor Virgil Murray said. "We've had this parade forever. We've had horses in the parade forever."

The parade is a decades-long tradition in the town, Murray said, and often includes tractors and bands.

Sandie Crilly, 46, of Willow Springs, Ill., said she was collecting Tootsie Rolls from the street with her 8-year-old son, 12-year-old niece and 2-year-old granddaughter when the horses ran toward them about halfway through the parade.

Someone yelled to get out of the way, she said.

"I could see it was two horses," Crilly said. "I could see they were running at full speed and they were harnessed together and I knew we were going to most certainly get hit, and as soon as it happened, everybody was crying and screaming."

Crilly, who was visiting her parents in Bellevue, said someone pulled her granddaughter to safety, but her niece was left with a broken left wrist and had her two front teeth knocked out. Everyone else suffered bumps and bruises, she said.

Paramedics treated victims in a nearby art gallery, Crilly said, and a triage area was set up near the Mississippi River, where volunteers held up tarps to shield the paramedics and injured from the sun and heat. Others brought the injured ice and water, she said.

"It was madness," Crilly said. "I mean we were in a triage. The town really came together. It was a huge community effort."

Carol Dietzel, house supervisor at Mercy Medical Center-Dubuque, said 10 patients were brought there, nine of them children. One child in critical condition was flown to University of Iowa Hospital in Iowa City, she said. Six children were treated and released.

Another child in critical condition was in surgery and also was expected to be transferred to University of Iowa Hospital, she said.

A third child and an adult, both in fair condition, were awaiting surgery at Mercy Medical Center.

Dietzel said other patients were taken to Finley Hospital in Dubuque, Jackson County Hospital in Maquoketa and Medical Associates Acute Care clinic in Dubuque. Two people taken to the clinic were treated and released.

Officials at Finley Hospital said a 70-year-old woman in serious condition was flown to University of Iowa Hospital.

The mayor said word went out via text message and phones that doctors and nurses were needed to treat the injured. He said all the injured were taken care of within an hour.

He said between 3,000 and 4,000 people attend the annual parade, many people coming in from rural areas and nearby towns.

"We've never really had any tragedy," Murray said. "Usually our biggest nemesis is if it rains. That's what we're always worried about."

The Dubuque Telegraph Herald reported that the out-of-control horses jumping curbs, hitting signs and cars and trampling onlookers as they ran along the parade route. They then hit a large street sign, flipping the buggy they were pulling and ejecting two people in it, the newspaper reported.

The animals eventually ran into a trailer hitched to a van.

Iowa Gov. Chet Culver said in a statement that he was thinking and praying for the victims.

"I am especially saddened because the accident occurred during the events celebrating Independence Day, which is a day that should be filled with pride and joy for all Iowans and Americans," Culver said.