Santa Fe Mayor-elect Jason Tabor, left, looks at Santa Fe Independent School District Police Chief Walter Braun during a press conference Monday. (Scott Olson/Getty Images)

An attorney for the 17-year-old charged with killing 10 people at a high school here last week said he still has no indication of what motivated the massacre and said he was not sure there would ever be a clear answer.

Even as authorities have not publicly identified a motive behind the bloodshed, they have slowly revealed more information about what happened inside the school, detailing the confrontation between police officers and Dimitrios Pagourtzis, the teen accused of committing the shooting.

Galveston County Sheriff Henry Trochesset said Monday that officers encountered the gunman within four minutes, “keeping him contained and engaged” so that other law enforcement officials could evacuate students and staff from the school.

“They contained him in that one area . . . so he did no more damage,” Trochesset said at a briefing, although it remained unclear when the last victim was shot or killed. Trochesset was responding to uncertainty about why 30 minutes elapsed before the teen was taken into custody on Friday morning. Many mass shootings occur in a matter of minutes. The Parkland, Fla., massacre in February lasted six minutes, police said, with 17 dead and 17 wounded.

Among the officers who confronted Pagourtzis was John Barnes, a school resource officer, who was critically wounded. Walter Braun, chief of the Santa Fe school district’s police force, said Barnes has had ups and downs since the shooting. “Today is a down day,” Braun said.

Police said the shooting suspect confessed to officers to carrying out the rampage that tore through a rural community outside Houston and reverberated around the world.

“That scene was horrific,” Trochesset said about what happened at the school, adding that his granddaughter was inside the school and three doors away from the gunfire.

Nick Poehl, an attorney for Pagourtzis, said he had met with his client three times since the shooting for a total of about 90 minutes. The teen is on suicide watch, police said.

Poehl said Pagourtzis, whom he described as “confused,” has not asked about who died during the shooting, and he did not say why the shooting began in the art room.

“There might not be a motive in the conventional sense,” Poehl said in an interview.

The attorney said his client’s family is stunned by what happened and said they saw no signs of trouble. Poehl said he was working to understand why his client allegedly attacked the school but did not know “if he’ll ever be able to tell me about what happened.”

On Monday, as police finally cleared out of their neighborhoods, residents who lived near two Pagourtzis family properties said they were shocked to learn that a neighbor they recalled as quiet and kind was capable of carrying out such a violent act.

Cherie and Jim Thompson said they have known the Pagourtzis family for more than a decade. Jim Thompson, 73, said he drove the teen to school until he was old enough to get his driver’s license , but he never expressed political views or gave any hint of trouble at home or school. He said most of their conversations centered around football.

“None of us saw this coming,” Cherie Thompson, 73, said. “He was very nice and very respectful and would have bent over backwards [for his neighbors]. He would feed our cat when we traveled.”

Helen Ramirez, who lives down the street from the Pagourtzises, used to babysit him and his younger sister. She also remembers a “polite, well-mannered” boy.

“We know he deserves punishment, and if he gets prison time, okay, but first give him psychiatric help,” said Ramirez, 80. “You just don’t take a boy that is good, and he turns into a creature overnight?”

Outside Santa Fe High School, the police tape had been taken down and replaced by 10 white crosses. Mourners, previously kept away, flocked to the school to leave flowers, balloons and stuffed animals.

Albert Pierce watched as his 16-year-old daughter wrote a note on the cross erected for Angelique Ramirez, one of the student victims.

“It’s been rough on her,” he said. “Her two best friends were killed.”

Pierce said he doubts that his daughter will return to school this year. She moved her sunglasses aside to wipe away tears before placing roses near one of the crosses.

Berman reported from Washington. Devlin Barrett in Washington contributed to this report.

Correction: In a previous version of this story, Jim Thompson said accused gunman Dimitrios Pagourtzis often played war games. Thompson later clarified that he was repeating information from the news, where others who knew Pagourtzis said he was an avid video game player. Thompson said he does not have independent knowledge of Thompson’s interest in such games. That information has been removed.