They called themselves "The Chain Gang" -- a group of bicyclists drawn together by zest for their sport, physical fitness and love of the outdoors whose day trip in the southwestern Michigan countryside ended tragically as a pickup truck plowed into them, killing five and injuring four others.

Stunned biking enthusiasts joined relatives and friends of the riders Wednesday in mourning them, leaving flowers, a commemorative "ghost bike" and a small wooden cross at the crash scene and gathering by the hundreds for a 5-mile "silent ride."

"We're all part of a community and this community needs to feel safe on the roads," Sheila Wood, an organizer of the ride, told the crowd of cyclists before they took off from a brew pub in nearby Kalamazoo.

Police said they had received complaints about a pickup being driven erratically and were searching for it minutes before the crash around 6:30 p.m. Tuesday on a two-lane road in Kalamazoo County's Cooper Township.

The driver, a 50-year-old man who fled but was caught by police shortly afterward, remained in custody Wednesday. County prosecutor Jeffrey S. Getting said he expected a report Thursday from the sheriff's department and other agencies that would help determine whether charges would be filed.

The prosecutor identified three of the bicyclists who were killed as Debra Ann Bradley, 53; Melissa Ann Fevig-Hughes, 42; and Suzanne Joan Sippel, 56, all of Augusta. The two others who died were Fred Anton "Tony" Nelson, 73, and Lorenz John "Larry" Paulik, 74, both of Kalamazoo.

Three others were listed in serious condition and a fourth in fair condition at area hospitals.

"There is no way to measure the grief we feel," said Renee Mitchell, president of the Kalamazoo Bicycle Club.

Mark Rose, who co-founded The Chain Gang about 15 years ago, said its members weren't "hardcore," but biked regularly for the exercise, enjoyment of being with friends and the "safety in numbers." He said he dropped out several years ago to focus on running.

"They were just casual cyclists who enjoyed the ride," said Rose, 58, of Galesburg, who participated in Wednesday's memorial ride wearing a shirt with a Chain Gang logo.

Sister Pam Owens, pastoral associate at Saint Thomas More Catholic Student Parish, said Nelson and Paulik were congregation members who were in "great shape" and had a well-known passion for cycling. Their group was 5 miles into a planned 30-mile ride when they were struck, she said.

"They were doing what they loved to do, and they were together. The family took solace in that fact," said Owens, who visited the crash site Tuesday night with the men's wives.

Nelson and Paulik also were devoted parishioners. They and their spouses helped lead a program that introduced newcomers to the Catholic faith, Owens said. They frequently helped people who had money troubles; Nelson assisted them in filling out tax returns.

Sippel was a science data manager at Michigan State University's Kellogg Biological Station and was married to an aquatic ecologist there, said director Kay Gross. She described Sippel as a "valued and cherished" colleague and said the husband and wife sometimes worked together on research projects.

"After her family, Suzanne's passion was clearly bike riding," Gross said in an email to The Associated Press, adding that Sippel often biked to work "and on more than one occasion I saw her heading out in rain and sleet to get home."

Sippel helped raise money to expand the nearby Kalamazoo River Valley Trail and lobbied to have part of it extend through university lands in the area, Gross said. An avid sportswoman, she took trips with her family that usually involved "hiking, biking, canoeing/kayaking or some outdoor adventure."

The couple had planned to take a sabbatical next year in Oregon, where their son will attend college, Gross said, adding, "I cannot express how much she will be missed."

As people streamed past the location of the fatal collision Wednesday, some kneeled in prayer.

"Ride on, friends, on the roads of heaven," one mourner wrote on a card left behind.

Bob Coffman, who said the force of the crash sent one of the victims' bicycles into his yard, placed the small wooden cross at the scene. A neighbor, Marc Laning, applied white paint to the "ghost bike" and attached it to the cross with a bungee cord, a gesture of respect to bicyclists killed by motor vehicles.

Some cycling advocates said they hoped the tragedy would inspire motorists to be more tolerant.

"Unfortunately, Michigan still worships the automobile and not everyone is yet comfortable with sharing the road with cyclists," said Ethan Alexander, founder of the Kalamazoo-based group Open Roads.

Gov. Rick Snyder issued a statement of condolence to the victims' families and the community on Wednesday. The Kalamazoo area still is dealing with the aftermath of the random fatal shootings of six people and wounding of two others in February. Jason Dalton, 45, is charged with murder and attempted murder in that case. His attorney told a judge Monday that Dalton is expected to enter an insanity plea.

"What we already know for certain is that Michiganders as a family are in mourning today as Kalamazoo struggles to understand another senseless tragedy," Snyder said.