CNN — Over a 24-hour period last Wednesday, several police officers from departments across the country were shot in the line of duty.

In Decatur, Illinois, two police officers were shot while making a traffic stop, and officers shot and killed the suspect, police said.

In Philadelphia, three SWAT team members were shot while executing a warrant, and officers shot and killed the subject, officials said.

And in Bristol, Connecticut, three officers were shot – two fatally – in an ambush attack while responding to a domestic disturbance report, and the surviving officer shot and killed the subject, police said.

The suspect fired over 80 rounds at police, according to a news release from the Connecticut inspector general’s office.

In all, from Monday through Friday last week, 13 police officers were shot – amid a heightened level of violence against law enforcement officers this year. From the beginning of the year through September 30, there were 252 officers shot, including 50 fatally, according to the Fraternal Order of Police, an organization representing US law enforcement officers.

That number of officers shot represents a 5% increase over the same period in 2021 and a 6% increase over the same period in 2020, according to the organization’s data. Last year, 73 officers were intentionally killed in the line of duty, the most since the terrorist attacks of September 11, 2001, according to FBI data.

The figures from the Fraternal Order of Police differ from the FBI’s data, which show 49 felonious killings and ten fatal ambush attacks, a slight decrease from last year’s total.

“I’m outraged. I’m disgusted. I’m wondering where the level of outrage and upset is outside of the law enforcement community,” Philadelphia Police Commissioner Danielle Outlaw said. “Right now things are wrong because the level of violence that we’re seeing against our law enforcement officers is just beyond outrageous.”

The increased violence against police officers in the last few years mirrors the broader rise in shootings and violence in the US since 2020.

Criminology experts such as Thomas Abt, a senior fellow at the Council on Criminal Justice, have cited a few potential explanations: the fraying of social connections due to the Covid-19 pandemic; the murder of George Floyd and resulting rise in public distrust of police and a surge in firearm sales and gun ownership.

While explanations for any violent crime vary, the FBI has tried to piece together an explanation of why some people attack police officers. A 2016 report, summarized in an FBI document released to law enforcement agencies in May 2017, examined 50 shootings of police officers and found that the assailants’ two key motives were a desire to escape arrest (40%) and their hatred of the police (28%).

There have been 63 “ambush-style” attacks on officers so far this year, resulting in 93 officers shot, including 24 fatally, according to the Fraternal Order of Police.

Officials said the fatal shooting in Bristol last week, which left two officers dead and one seriously wounded, was one such incident. Police had received a 911 call about a possible domestic incident between two siblings and arrived to find a suspect who shot at them, authorities said. Officials described the 911 call as “a deliberate act to lure law enforcement to the scene.”

Bristol Police Chief Brian Gould said the fallen officers epitomized bravery in policing, just like so many officers do every day.

“They answered a call to duty, and they responded without hesitation,” he said. “And that’s what they did every night before that. And that’s what all our officers do and will continue to do.”

There are even risks to those officers not on duty. In Raleigh, North Carolina, on Thursday, a 15-year-old opened fire and killed five people, including Gabriel Torres, a 29-year-old off-duty police officer who was on his way to work. Two people, including a responding officer, were also shot and wounded. The suspect is hospitalized in critical condition and will be charged as an adult, authorities said.

In one of four 911 calls obtained by CNN, a caller told a dispatcher that the shooter was wearing camouflage and looked like he was 16. The caller said the gunman “walked by and shot” a police officer “for no reason.”

Outlaw, the Philadelphia police commissioner, said she felt a pit in her stomach when she learned last week three of her department’s officers had been shot.

“We signed up to do this understanding the risk, understanding the danger, but we did not sign up for these jobs to be martyrs. We just didn’t,” she said.

“It has to go beyond people like myself, police chiefs or superintendents or commissioners that are speaking out against this. Everyone has to come together and recognize that violence against our police officers is intolerable just as violence in other parts of our communities is intolerable as well.”