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

Two-thirds of young African-Americans and 4 in 10 Hispanics say that they or someone they know have 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 want a police presence in their communities.

GenForward is a survey of adults 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.

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 the police as more serious problems and young whites see violence against the police as more serious.

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

Webb, who is black, said she was arrested last November by two officers — one white, the other black.

“They threw me in the police car and when I gave them my story the other officer who was white gave me a look,” she said. “While the officer of color was asking questions and being nice, the other officer got in the car and started yelling at me. He told me to just shut up.”

The charges against her eventually were dropped by a judge, she said.

The new poll shows young people, including young blacks and Hispanics, do want a police presence in their communities. In fact, most support adding more police or armed security guards in public places like schools, movie theaters and malls.

Billy Busby, 24, of Atlanta, said he was working a security job and helping police in Myrtle Beach, S.C., with crowd and traffic control during a popular event in May when he was approached by a white officer.

“The officer came up to me and said, ‘What are you doing here?' I said, ‘I'm sorry, I'm doing my job.' She said, ‘You need to move or I'm going to arrest you,'?” said Busby, who is black.

Busby said his supervisor showed up, vouched for him and defused the situation.

Some officers in southern Mississippi target Hispanics, thinking they're in the U.S. illegally, said Patience Buxton, 28, who owns a company in Forest, Miss., that shuttles people back and forth to various appointments.

Buxton is biracial but identifies as white and says many of her customers are Hispanic.

“I know they are looking at me,” Buxton said of officers. “I get nervous myself. ... They've called me a coyote, asked me if I'm transporting illegals. They abuse their authority.”

The poll of 1,940 adults age 18 to 30 was conducted July 9 to 20 using a sample drawn from the probability-based GenForward panel, which is designed to be representative of the U.S. young adult population. The margin of sampling error is plus or minus 3.8 percentage points.

The survey was paid for by the Black Youth Project, using grants from the John D. and Catherine T. MacArthur Foundation and the Ford Foundation.

Respondents were selected randomly and interviewed online or by phone.