An 18-year-old gunman fired indiscriminately while roaming a residential street in Farmington, N.M., on Monday morning, killing three people before the police arrived and killed the suspect, the authorities said. Six other people, including two officers, were injured.

The authorities received several reports of shots fired near Dustin Avenue and Ute Street just before 11 a.m., Chief Steve Hebbe of the Farmington Police Department said in a video statement released on Monday night, adding that the rampage appeared to be “purely random.”

Chief Hebbe said that the gunman, whom he did not name, had used at least three different weapons, including an “AR-style rifle,” a gun commonly used in mass shootings, as he roamed through the neighborhood, randomly firing “at whatever entered his head to shoot at” including at least six houses and three cars.

Officers located the shooter in the 700 block of North Dustin Avenue, Chief Hebbe said, where they shot and killed him.

The two injured police officers — one from the Farmington Police Department, and a state police officer — were treated at the San Juan Regional Medical Center in Farmington, the authorities said. The state police officer had been released by Monday night and the other officer was “doing well,” according to Chief Hebbe.

Earlier on Monday, the authorities said that nine people, not including the shooter, had been injured, before lowering that number to six.

The conditions of the others who were injured were not immediately known, and the authorities did not release the names of any victims or the suspect.

The motive for the shooting remained unclear. In an earlier news conference, Deputy Chief Baric Crum said it was not immediately known whether the suspect had any criminal history or why he was in the neighborhood. The chief said that officers were inspecting several blocks to piece together what had happened, and that it was unclear whether a video circulating on social media purporting to show the suspect being shot was real. He said it was unclear whether the suspect had entered any homes.

The shooting sent shock waves through the city of about 46,000 people, which is about 140 miles northwest of Albuquerque near the Navajo Nation reservation. The city serves as a commercial hub for nearby oil-producing areas as well as much of northwestern New Mexico.

Matt Mizell, the lead pastor of Hills Church, which hosted a vigil for the victims on Monday evening, said that the community, which also suffered a nearby school shooting in 2017, was reeling from the carnage. “It has shaken the community to its core,” he said.

Joseph Robledo, a 32-year-old tree trimmer, told The Associated Press that he had rushed home after learning that his wife and 1-year-old daughter had sought shelter in the laundry room when gunshots rang out.

A bullet went through his daughter’s window and room, without hitting anyone, Mr. Robledo said, adding that he and others had administered first aid to a woman who appeared to have been wounded while driving through the neighborhood. “We’ve been doing yard work all last week,” Mr. Robledo told The A.P. “I just thank God that nobody was outside in front.”

Gov. Michelle Lujan Grisham of New Mexico said on Twitter that she was “deeply upset by the tragic violence” and that her administration would “not stop fighting the epidemic of gun violence.”

In a joint statement, members of New Mexico’s congressional delegation said that they were “devastated” by the shooting and added that they would continue working to ensure federal resources were made available.

“Although Congress took major action to combat gun violence last year through the Bipartisan Safer Communities Act, today is a painful reminder that we must do more,” the lawmakers, all Democrats, said. “We are committed to fighting for sensible gun safety measures that will keep New Mexicans safe.”

The shooting is being investigated by the Farmington Police Department, the San Juan County Sheriff’s Office and the New Mexico State Police. The Bureau of Alcohol, Tobacco, Firearms and Explosives also responded, its Phoenix field office said.

“There are no other known threats at this time,” the police said.

Farmington Municipal Schools were placed under a preventive lockdown after 11 a.m., which was lifted about two hours later, the school system said.

Last month, officers with the Farmington Police Department shot and killed an armed man while responding to a domestic violence call at the wrong home. In 2017, in the nearby town of Aztec, a former student at Aztec High School fatally shot two students at the school before killing himself.

Simon Romero contributed reporting.