The police continuously revise tactics to face threats. If they dont, someone ends up dead.
Suicide bombers present a challenge to a police officer who confronts him. You have to stop this guy from killing people, and you are a patrolman armed with a pistol of maybe a shotgun. You cant fire center mass because you may detonate the charge and people ( including yourself) die.
Most of the tactics developed to deal with suicide bombers come from Israel, and they arent pretty. They range from sacrificing yourself to blunt the explosion and fragments ( the jump on a hand grenade approach) to talking them down with negotiations.
The bombers have evolved too. Now they shoot their way into an intended target to remove resistance so they can explode themselves.
Standard rules dont apply to suicide bombers.
This isn't going to be easy. I wonder if there's a way to develop a really cheap portable sensor similar to a fire alarm. I've been working on a project that detects (specifically) marijuana smoke and alarms accordingly.
The trick is to make it cheap enough.