SHOW LOW, Ariz. (AP) — Authorities were trying to determine why a 35-year-old man driving a pickup truck plowed into bicyclists during a community road race in Arizona, critically injuring six riders.

The suspect, whose name hasn’t been released, was hospitalized in critical but stable condition after fleeing the crash scene Saturday and being shot by police outside a nearby hardware store in the mountain town of Show Low, about a three-hour drive northeast of Phoenix.

“We don’t know the motivation,” city spokeswoman Grace Payne told The Associated Press.

Four of the injured riders were hospitalized in critical condition with two others in critical but stable condition as of Saturday. One was flown to a hospital near Phoenix.

Authorities didn’t immediately provide any updates Sunday.

“This has been a horrible event,” police spokeswoman Kristine Sleighter said in a statement. “Our community is shocked at this incident and our hearts and prayers are with the injured and their families at this time.”

Witnesses said helmets, shoes and crumpled and broken bicycles were strewn across the street after the crash, and a tire was wedged into the grill of the truck, which had damage to its top and sides and a bullet hole in a window.

Police said a Ford pickup truck struck the bicyclists about 7:25 a.m. Saturday in downtown Show Low during the annual 58-mile (93-kilometer) Bike the Bluff race that had 270 participants.

Tony Quinones, of Santa Fe, New Mexico, told the New York Times that he had been riding for about six minutes with other cyclists ages 55 and over when a black pickup that had been driving in the opposite direction crossed over three lanes and headed toward the cyclists.

Quinones said he assumed the driver was turning into a parking lot. Instead, the driver plowed directly into the cyclists ahead of the 55-year-old Quinones.

“He drove his truck directly and intentionally into our group, and you could hear him accelerate,” Quinones said, adding that he saw bikes and bodies flying.

After the driver hit a telephone pole, cyclists ran up to the truck and started pounding on the windows, screaming at the driver to get out, Quinones told the Times.

But rather than stop, he said the driver hit the accelerator and backed out, drove down the road, made a U-turn and then headed back toward the cyclists.

Payne said the driver did not comply when officers tried to arrest him, but the circumstances of the shooting were not immediately released.

The Navajo County sheriff’s office and Arizona Department of Public Safety were helping with the investigation.