When police believe a suspect could harm or kill them, they're usually trained to fire as many gunshots as it takes to bring that suspect down.

The shooting itself almost always lasts only seconds. But questions about whether the number of shots officers fired was warranted -- or whether that suspect posed a deadly threat to an officer in the first place -- can persist long after that suspect is wounded or killed.

Since George Floyd's killing in May, police have had to answer to the public as protests over police brutality and systemic racism continue nationwide.

This week, the spotlight is on police in Kenosha, Wisconsin, for the shooting of Jacob Blake, a 29-year-old father of three who was shot seven times while his children watched from his car. Blake is in serious condition at a local hospital, his family told CNN.

Law enforcement departments have long fielded questions about why officers fired as many shots as they did at a suspect. Police shootings aren't a science -- they're usually high-stress situations where adrenaline takes over an officer's response -- but some factors explain why officers shoot as many times as they do.

POLICE SHOOT UNTIL THEY'VE 'TERMINATED A THREAT'

The "textbook answer" is that officers fire until they've terminated a threat, according to Seth Stoughton, an associate professor at the University of South Carolina School of Law who studies policing.

Officers use deadly force on a suspect they perceive to be an imminent threat of death or bodily harm to the officers or others. In training, police are told to use force until that person no longer presents a threat, Stoughton said.

The number of shots it takes to "terminate a threat" depends on the circumstances.

"Sometimes firing multiple shots makes complete sense," said Stoughton, a former officer. "Sometimes firing multiple shots or the sheer volume or shots than officers fire doesn't make sense."

If officers are using deadly force, they're usually trained to not pause their fire and to shoot in quick succession -- taking a break to assess the suspect they're shooting at could give that suspect time to harm them or others, he said.

And legally, the number of shots officers fire often doesn't matter, he said: Under the Fourth Amendment, officers must have had reason to believe the suspect they fired on was a threat who could've killed them or caused great bodily harm. The court determines whether the officer was reasonable in making that assessment, not whether the number of shots fired was reasonable.

MULTIPLE OFFICERS OFTEN SHOOT AT ONCE

High shot counts may be attributed to a phenomenon called "sympathetic fire" or "reflexive fire," which occurs when one officer fires on a suspect, so one or more officers with them start firing, too, even if they haven't immediately perceived the suspect to be a threat, Stoughton said.

This can create confusion among the officers, though, he said: They may mistake another officer's shots for the suspect firing shots at them, which could cause them to continue to shoot needlessly.

THEY MISS SHOTS

Shooting accuracy varies based on how close an officer is to a suspect -- but data shows that they're often not accurate shots.

A 2019 study of the Dallas Police Department found that in more than 130 shootings, officers struck their targets 35% of the time. Most of their shots were misses. And a 2006 analysis, which examined a number of major metropolitan police department shootings throughout the late '80s and early '90s, found that hit rates rarely exceeded 50%. Some departments, including the New York Police Department in 1990, hit only about 23% of targets.

They're often stressed and not counting their shots

The anxiety and adrenaline of a high-stress deadly force incident may cloud officers' judgment, said Cedric Alexander, a police training consultant and 39-year law enforcement veteran.

This can lead to some officers firing an unwarranted number of rounds. Many officers don't recall how many shots they fired when interviewed immediately after a shooting, he said.

"Some officers will testify or give a statement immediately after that they fired three to four shots when they actually fired 10 to 11 shots," Stoughton said. "In high-stress, adrenaline, heart-pounding moments, an officer is not counting their shots."

The point of training is to prepare officers for those high-stress incidents where they may be required to use deadly force. But an officer who perceives that they're in immediate danger "may just keep pulling the trigger until their brain catches up with them," Stoughton said.

THEY'RE USING A QUICK-FIRING WEAPON

The type of firearm an officer uses may impact the number of shots they fire. If they're using the typical semi-automatic weapon, Alexander said, they may have as many as 15 rounds in their gun that they can fire in quick succession.

IN MANY CASE, THEIR TRAINING IS LACKING

Many officers resort to using firearms if they're not comfortable apprehending a suspect with physical force first, Stoughton said. In circumstances where officers don't know whether a suspect is armed, an officer's lack of confidence could cause them to fatally shoot an unarmed person.

"We should not overlook the role of fear in officers' use-of-force decision-making," Stoughton said.

Officers are trained in use of force more than almost any other skill, Stoughton said. But they often don't receive as much training in physical apprehension or "empty hand techniques" that could prevent a loss of life.

"(That lack of training) can lead them to escalate to higher-force options, rather than rely on those physical skills if they were more confident in them," he said. "The more comfortable an officer is with physical apprehension skills, the less they need to escalate to intermediate weapons or a firearm."