“I know some have strong feelings about gun rights but I want you to know I’ve hit rock bottom and I am not interested in your views as it pertains to this issue,” he wrote. “Please do not post anything about guns aren’t the problem and there’s little we can do. My feelings won’t be hurt if you de-friend me and I hope yours won’t be if you decide to post about your views and I de-friend you.”

On Saturday, the authorities said the student who opened fire, Dimitrios Pagourtzis, had confessed. There have been so many school shootings recently — including one in Parkland, Fla., in which a 19-year-old former student killed 17 people — that to some students at Santa Fe High School the shooting on Friday was hardly a surprise.

In his Facebook post, which had elicited more than 16,000 reactions as of late Saturday, Chief Acevedo said the days after the shooting were a time for “the asking of God’s forgiveness for our inaction.” He specifically called out “the elected officials that ran to the cameras today, acted in a solemn manner, called for prayers, and will once again do absolutely nothing.”