"Getting hurt like that or getting killed is not that frequent, but no matter how much you prepare, these things happen. It's part of the dangers of the job," he said.
But it's that shared risk that adds to the "sense of family" that brought officers around the region together to mourn Schneider's loss.
Police say Schneider was rounding a corner inside the house on Roberts Avenue in Catonsville when he was shot.
Police say he returned fire, striking his alleged assailant. Tevon Smith, 25, died later at Maryland Shock Trauma Center.
Police say Smith was not the suspect police were seeking.
Shirey said tactical units train regularly for different scenarios, and attempt to use intelligence such as who the occupants are, what the floor plan might be and whether there are bystanders.
"They are planned in as much detail as we could possibly get together prior to getting in," he said. But "sometimes you get caught by surprise, there are extraneous factors you cannot predict."
Typically, he said, such officers wear heavier gear than the average patrol officer. But even with such precautions, the officers can be vulnerable.
"There are chinks in the armor," Shirey said.
Baltimore County police said Schneider was wearing a bullet-proof vest, but one round struck him in the back.
Through the department, Schneider's family declined to comment. Officers in his hometown of Manchester in Carroll County closed the roadway that leads to his house. A handful of police cruisers were in the area, allowing only residents to pass through.
Schneider's funeral has been scheduled for 10 a.m. Saturday at St. Bartholomew Roman Catholic Church on Hanover Pike in Manchester. A viewing will be held from 2 p.m. to 9 p.m. Friday at the Eckhardt Funeral Chapel on Charmil Drive in Manchester.
Baltimore Sun Media Group reporters Blair Ames and Ian Duncan contributed to this article.