DUXBURY — A quiet spring weekend was interrupted by chaos early Sunday morning, when a shotgun-wielding Maine man allegedly fired at three random people, injuring two, in Duxbury, police said.

Lucas McPherson, 25, of Mapleton, Maine, was subdued by Duxbury police officers after he allegedly fired in separate incidents on at least two drivers and a man letting his dog out, then attacked a police officer with a knife, police said.

At a press conference late Sunday afternoon, Duxbury Police Chief Matthew M. Clancysaid McPherson would be charged with a host of crimes including attempted murder, assault and battery on a police officer, and illegal gun possession.

Clancy said there is no apparent connection between McPherson and the three victims; each shooting, he said, appeared to be “completely random.’’

“This is an extremely troubling and serious event,’’ Clancy said. “We could have had [three] citizens killed and a police officer who could have justifiably killed’’ the suspect.

McPherson has no obvious connection to Duxbury or Massachusetts, Clancy said, and has only a minor criminal record in Maine. It was unknown how long McPherson has been in the South Shore area, or why he opened fire, Clancy said.

At the conference, Clancy said McPherson was probably shooting people while driving his Chevrolet Impala, his double-barreled shotgun pointed outside his window.

“That is clearly a big piece of our investigation. Why? How? And why here?’’ Clancy said. “This is random and completely out of character for our community.’’

The first victim, a 33-year-old Marshfield man, was driving on Tremont Street near Town Hall at about 1:15 a.m. when he was shot in the abdomen by someone in a passing car, Clancy said. The victim drove to the Duxbury fire station to seek help.

As officers began searching for a suspect, they were approached by a resident who told them he had also been shot by someone in an Impala, Clancy said. That man had been letting his dog out.

Both victims suffered non-life-threatening injuries, Clancy said in the statement.

The third victim, a 37-year-old Pembroke woman, did not come forward until later Sunday, after she checked her car and discovered holes. After police inspected her vehicle, they determined that the woman was likely shot at as she traveled along Tobey Garden Street at about 1:30 a.m.

The Pembroke woman was not injured, Clancy said. At the time, she thought her car had backfired, he said. The victims were not identified.

Police arrested McPherson shortly after the second victim was found. According to Clancy, McPherson had to be hit twice with a Taser by a Duxbury officer, who was assisted by officers from Kingston.

Police recovered a shotgun believed to be used in the shootings inside the car, Clancy said.

“Our police department did an incredible job,’’ said Duxbury town manager, René J. Read, after the press conference. “Everything worked out here the best that it could.’’

Both Clancy and Read stressed that they were thankful for the work of the Duxbury police officers, who resolved the situation without further injuries.

In similar incidents in Massachusetts involving armed citizens, including last week in Everett, police have shot and killed suspects carrying knives. Clancy said he believes lethal force would have been justified in this arrest — had the arresting officer used a gun instead of a Taser.

As officers were transporting McPherson to Plymouth County Correctional Facility, he attempted to attack two other officers, Clancy said. Police said McPherson was then taken to a hospital for a mental health evaluation but has since been taken to jail.

He is scheduled to be arraigned Monday in Plymouth District Court, Clancy said.

When reached by telephone, a McPherson family member in Maine declined to comment about the shootings.

“We’re still trying to figure out what happened ourselves,’’ the person said.

However, Clancy said the family has spoken with law enforcement in Duxbury and said McPherson had acted strangely in the past few months. Authorities also conducted tests for possible drug use, Clancy said.

South Shore residents reacted to the shooting and arrest with shock and horror. At a youth baseball game near the town library, several fathers said they were worried about the random nature of the shootings and concerned about the safety of their children.

“It’s disturbing,’’ said one father, who asked not to be identified. “That type of thing doesn’t happen around here.’’

The father said he is in the process of moving to Duxbury and the shooting gave him a moment of pause.

Read, the town manager, urged residents to remain calm.

“Why’d he come here?’’ Read asked. “Who knows.’’

Aimee Ortiz of Globe staff contributed to this story. Astead W. Herndon can be reached at astead.herndon@globe.com.