LOUISVILLE, KY. -- Hours after a Kentucky grand jury brought no charges against Louisville police for Breonna Taylor's death and protesters took to the streets, authorities said two officers were shot and wounded Wednesday night during the demonstrations expressing anger over the killings of Black people at the hands of police.

Interim Louisville Police Chief Robert Schroeder said a suspect was in custody but did not offer details about whether that person was participating in the demonstrations. He says both officers are expected to recover, and one is undergoing surgery.

He says the officers were shot after investigating reports of gunfire at an intersection where there was a large crowd.

Several shots rang out as protesters in downtown Louisville tried to avoid police blockades, moving down an alleyway as officers lobbed pepper balls, according to an Associated Press journalist. People covered their ears, ran away and frantically looked for places to hide. Police with long guns swarmed the area, then officers in riot gear and military-style vehicles blocked off roadways.

The violence comes after prosecutors said two officers who fired their weapons at Taylor, a Black woman, were justified in using force to protect themselves after they faced gunfire from her boyfriend. The only charges were three counts of wanton endangerment against fired Officer Brett Hankison for shooting into a home next to Taylor's with people inside.

The FBI is still investigating potential violations of federal law in connection with the raid at Taylor's home on March 13.

Ben Crump, a lawyer for Taylor's family, denounced the decision as "outrageous and offensive," and protesters shouting, "No justice, no peace!" immediately marched through the streets.

Scuffles broke out between police and protesters, and some were arrested. Officers fired flash bangs and a few small fires burned in a square that's been at the centre of protests, but it had largely cleared out ahead of a nighttime curfew as demonstrators marched through other parts of downtown Louisville. Dozens of patrol cars blocked the city's major thoroughfare.

Demonstrators also marched in cities like New York, Chicago, Washington, D.C., Atlanta and Philadelphia.

Taylor, an emergency medical worker, was shot multiple times by white officers who entered her home during a narcotics investigation. State Attorney General Daniel Cameron said that while the officers had a no-knock warrant, the investigation showed they announced themselves before entering. The warrant used to search her home was connected to a suspect who did not live there, and no drugs were found inside.

Along with the killing of George Floyd in Minnesota, Taylor's case became a major touchstone for nationwide protests that have drawn attention to entrenched racism and demanded police reform. Taylor's image has been painted on streets, emblazoned on protest signs and silk-screened on T-shirts worn by celebrities. Several prominent African American celebrities joined those urging that the officers be charged.

The announcement drew sadness, frustration and anger that the grand jury did not go further. The wanton endangerment charges each carry a sentence of up to five years.

Morgan Julianna Lee, a high school student in Charlotte, North Carolina, watched the announcement at home.

"It's almost like a slap in the face," the 15-year-old said by phone. "If I, as a Black woman, ever need justice, I will never get it."

Gov. Andy Beshear, a Democrat, said he authorized a limited deployment of the National Guard. He also urged Cameron, the state attorney general, to post online all the evidence that could be released without affecting the charges filed.

"Those that are currently feeling frustration, feeling hurt, they deserve to know more," he said.

The case exposed the wide gulf between public opinion on justice for those who kill Black Americans and the laws under which those officers are charged, which regularly favour police and do not often result in steep criminal accusations.

At a news conference, Cameron spoke to that disconnect: "Criminal law is not meant to respond to every sorrow and grief."

"But my heart breaks for the loss of Miss Taylor. ... My mother, if something was to happen to me, would find it very hard," he added, choking up.

But Cameron, who is the state's first Black attorney general, said the officers acted in self-defence after Taylor's boyfriend fired at them. He added that Hankison and the two other officers who entered Taylor's apartment announced themselves before entering -- and so did not execute the warrant as "no knock," according to the investigation. The city has since banned such warrants.

"According to Kentucky law, the use of force by (Officers Jonathan) Mattingly and (Myles) Cosgrove was justified to protect themselves," he said. "This justification bars us from pursuing criminal charges in Miss Breonna Taylor's death."

Cameron said an FBI crime lab determined that Cosgrove fired the bullet that killed Taylor.

Taylor's boyfriend, Kenneth Walker, opened fire when police burst in, hitting Mattingly. Walker told police he heard knocking but didn't know who was coming in and fired in self-defence.

Cameron, who is a Republican, is a protege of Senate Majority Leader Mitch McConnell and has been tagged by some as his heir apparent. His was also one of 20 names on President Donald Trump's list to fill a future Supreme Court vacancy.

At a news conference, Trump read a statement from Cameron, saying "justice is not often easy." He later tweeted that he was "praying for the two police officers that were shot."

Democratic presidential candidate Joe Biden and his running mate, Kamala Harris, are calling for policing reform.

Biden says that while a federal investigation continues, "we do not need to wait for the final judgment of that investigation to do more to deliver justice for Breonna." He said the country should start by addressing excessive force, banning chokeholds and overhauling no-knock warrants.

"We must never stop speaking Breonna's name as we work to reform our justice system, including overhauling no-knock warrants," Harris said on Twitter.

Hankison was fired on June 23. A termination letter sent by interim Louisville Police Chief Robert Schroeder said he had violated procedures by showing "extreme indifference to the value of human life" when he "wantonly and blindly" fired his weapon.

Mattingly, Cosgrove and the detective who sought the warrant, Joshua Jaynes, were placed administrative reassignment.

Last week, the city settled a lawsuit against the three officers brought by Taylor's mother, Tamika Palmer, agreeing to pay her $12 million and enact police reforms.

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Lovan reported from Frankfort, Kentucky. Associated Press writers Claire Galofaro, Bruce Schreiner and Rebecca Reynolds Yonker in Louisville, Kentucky, Kevin Freking in Washington, Aaron Morrison in New York and Haleluya Hadero in Lancaster, Pennsylvania, contributed.

Hudsbeth Blackburn is a corps member for the Associated Press/Report for America Statehouse News Initiative. Report for America is a non-profit national service program that places journalists in local newsrooms to report on undercovered issues.

Correction:

This story has been updated to clarify that, according to the investigation, officers did not execute the warrant as a no-knock warrant, not that they didn't use a no-knock warrant. It also has been edited to clarify that the shots fired by Hankison entered another home with people inside, not several homes.