DETROIT — Crystal Webb cringes whenever a patrol car appears in her rearview mirror. She also never wants to see the inside of a police station again.

Her personal experience with police, plus recent fatal shootings of unarmed black men by white officers, has led the Apple Valley, California, mother of two to ask: Who are the good guys and who are bad?

“You are the people I’m supposed to go to when I’m in trouble,” Webb says of police.

Two-thirds of young African-Americans and 4 in 10 Hispanics say that they or someone they know has experienced violence or harassment at the hands of the police, according to a new GenForward poll. That includes about 2 in 10 in each group who say that was a personal experience, including about 3 in 10 black men who say the same.

But the poll also shows that young people still desire a police presence in their communities.

GenForward is a survey of adults age 18 to 30 by the Black Youth Project at the University of Chicago with the Associated Press-NORC Center for Public Affairs Research. The first-of-its-kind poll pays special attention to the voices of young adults of color, highlighting how race and ethnicity shape the opinions of a new generation.

Those poll results come after the killing of several young black men by police around the country. Two of the more recent killings were the July 5 shooting death of Alton Sterling during a struggle with officers in Baton Rouge, Louisiana, and the fatal shooting of Philando Castile the following day by an officer in a suburb of St. Paul, Minnesota.

Those shootings were followed by the July 7 killing of five officers in Dallas by a black gunman during a protest against police shootings of black suspects. Two police officers and one sheriff’s deputy were shot and killed by a black gunman during a July 17 ambush in Baton Rouge, Louisiana.

About 6 in 10 young adults consider the killings of black people by the police and violence against the police as extremely or very serious problems, according to the poll. But young African-Americans and Hispanics see killings by police as more serious problems and young whites see violence against the police as more serious. Most, especially blacks and Hispanics, say not-guilty verdicts for three Baltimore police officers charged in the April 2015 death of Freddie Gray give them less confidence in the police.

Gray, 25, was fatally injured while handcuffed and shackled in the back of the van.

Among young whites and Asians in the new poll, just 3 in 10 say they or someone they know has experienced police harassment, and just 1 in 10 white and 1 in 20 Asians say that was a personal experience.