Law enforcement officials investigate the scene of a shooting Thursday in a parking lot behind a dentist’s office in Westminster, Colo. (David Zalubowski/Associated Press)

A boy, his brother and his mother are among the victims of a shooting that police in Colorado say was prompted by a road-rage incident.

The shooting happened Thursday afternoon outside a dental clinic in Westminster, Colo., north of Denver. Police found the victims in the parking lot of Comfort Dental, suffering from gunshot wounds.

The boy later died. His mother and brother are in critical condition, police said. A fourth victim, a man unrelated to the other three, is expected to survive.

Jeremy Webster, 23, who has been charged with murder, assault and other charges, did not know the victims, and the shooting appears to have “stemmed from a road rage,” according to a news release from the Westminster Police Department. Police did not elaborate further on what might have pushed Webster to shoot the victims.

Webster had initially escaped, but was caught a few hours later. Police found his vehicle, a 2010 Toyota Corolla, about 40 miles away.

Police found the victims in a parking lot behind a Colorado dental clinic lot suffering from gunshot wounds. (David Zalubowski/Associated Press)

The owner of a nearby car shop told NBC affiliate KUSA that he heard at least seven gunshots and watched a man run down a sidewalk near the dental clinic.

“Like somebody was taking their time aiming at whatever they were shooting at,” Shaun Licius told KUSA. “It wasn’t like they were out just shooting targets.”

James Sisneros said he had just dropped off his daughter at another dental clinic nearby when he heard gunshots. The nearby clinic was placed on lockdown as police interviewed witnesses, he told NBC affiliate KUSA.

“They let me know my daughter is okay, so it’s some relief,” Sisneros said. “But it’s still stressful because she’s still locked inside.”

For Sisneros, the shooting left him feeling uncertain.

“In today’s world you never know where it’s going to happen, whenever someone loses their trigger,” he told CBS Denver.

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