US President Barack Obama issued a call for the United States to tackle racial disparities in the criminal justice system, after two new police shootings of African-Americans leapt into the headlines this week.
"We have seen tragedies like this too many times," Obama said from Warsaw, after arriving after midnight ahead of a summit later Friday.
"All of us as Americans should be troubled by these shootings because these are not isolated incidents. They are symptomatic of a broader set of racial disparities that exist in the criminal justice system."
On Thursday, the governor of the north-central US state of Minnesota denounced as racially motivated the shooting of a black man by a police officer during a traffic stop.
"Would this have happened if the driver and the passengers were white? I don't think it would have," Governor Mark Dayton said in a press conference.
The US Justice Department was monitoring a state investigation of the shooting of Philando Castile, 32, near Minneapolis, Minnesota, days after the launch of a federal investigation into a similar incident in the southern state of Louisiana.
In a statement, the Justice Department said it was "prepared as necessary to conduct further investigation and consider this matter under applicable federal law."
Dayton has asked the Justice Department to begin an immediate independent investigation into Castile's killing.
"There's a big chunk of our fellow citizenry that feels as if because of the color of their skin they are not being treated the same," said Obama, who took office in 2009 as the first African-American president.
"That hurts, and that should trouble all of us," he said. "All fair-minded people should be concerned."
Castile was shot four times by an officer late Wednesday as he tried to get out his wallet after being pulled over for a broken tail light, police said.
His fiancee, Diamond Reynolds, recorded the aftermath using Facebook Live, as Castile bled profusely while the officer continued pointing his sidearm at him. Castile later died at the county hospital.
During the traffic stop before the shooting, Castile informed police that he had a permit to carry a concealed weapon and was armed, Reynolds said.
Her 4-year-old daughter was in the back seat of the car during the entire incident.
Dayton stressed that state authorities were taking the incident very seriously and said it appeared that Castile had not done anything to provoke the police officer. He expressed horror that the man had not been given first aid on the scene and that Reynolds and been handcuffed and taken to the police station.
"Nobody should be shot and killed for their tail light being out. Nobody should be shot and killed in the seat of their car," he said.
The officer involved has been placed on paid administrative leave, said Jon Mangseth, interim police chief in suburban St Anthony, Minnesota.
Castile's death cames a day after the death of Alton Sterling, a 37-year-old black man shot by police in Baton Rouge, Louisiana, after officers responded to a complaint about a black male selling CDs and threatening the caller with a gun. The US Justice Department said Wednesday it would investigate Sterling's killing.
Both deaths sparked outrage on social media and calls by civil rights leaders and politicians to address the issue of police brutality against African-Americans.
"I am horrified that we are forced to confront yet another death of a young African-American man at the hands of law enforcement," Minnesota Senator Al Franken said. "They deserve nothing less than a full and independent investigation into Philando's death by the Department of Justice."
Obama emphasized that abhorrence toward unjustified shootings by police should not be seen as a condemnation of all officers, who put themselves at risk to do dangerous work.
"All lives matter. But the data shows that black folks are more vulnerable to these kinds of incidents," he said.
Obama urged Americans to approach the issue with compassion.
"I just ask folks to step back and think, what if this happened to someone in your family? How would you feel?" he asked.
"To be concerned about these issues isn't political correctness, it's being American."