CHICAGO (CBS) — About 100 medical students and doctors staged a 16-minute “die-in” Thursday morning outside City Hall, joining the call for Mayor Rahm Emanuel to resign over the fatal police shooting of 17-year-old Laquan McDonald.

Dressed in white lab coats, the protesters lay on the sidewalk outside City Hall, just across the street from Daley Plaza, for 16 minutes – one minute for each time McDonald was shot by Officer Jason Van Dyke on Oct. 20, 2014.

Echoing chants heard at many other protests in the wake of Van Dyke being charged with murder, and the release of the video showing the officer shooting McDonald, the protesters shouted “step down, now!” and “16 shots and a cover-up!” after the die-in.

Many in the crowd held up signs reading “Rahm is not healthy for Chicago” and “#WhiteCoats4BlackLives.”

Sheena Harmon, a third-year resident at Rush, said the justice system needs to be held accountable for its actions, “not only including the misuse of deadly force by police officers, but also the lack of prosecution for these heinous acts, and the misrepresentation of minorities and those of lower socioeconomic status.”

“I am here to support the numerous black men, including Laquan McDonald, who have lost their lives unjustly at the hands of the very entity created to protect us,” she said.

Ashley Czworniak, a student at Chicago College of Osteopathic Medicine, said Emanuel has allowed institutionalized racism “continue for far too long” in Chicago.

Czworniak said she’s not anti-police, as she’s from a police family, but she said she wanted “to stand against unlawful killing.”

“Even more so, to stand against obstruction of the law for the purpose of political gain,” she said. “That is exactly what Rahm Emanuel did by suppressing the issue of Laquan McDonald’s death until after his re-election. I take issue with a powered official valuing black lives enough to use them as pawns for the purpose of re-election, but not valuing them enough to be honest with them about the violence that happens in their own communities.”

Cworniak said Emanuel’s apology on Wednesday for the McDonald shooting is not enough to solve the city’s policing problems.

“We need to work moment by moment to dismantle the power of people who think and act as if laws and their protections do not apply equally to all people,” she said. “Yesterday, Mayor Rahm Emanuel said that the first step in the healing process for this city was to be his. Step down.”

Scott Goldberg, a fourth-year medical student at the University of Chicago, said the doctors and medical students felt it was their responsibility to stand with people whose lives are affected by gun violence every day.

“They face the effects in terms of psychological and physical trauma, and we want to stand here on behalf of our patients,” he said.

The activists said the Black Lives Matter movement is about more than violent crime, it’s also a public health issue.

“We’ve seen the dramatic differences in health outcomes for different populations in our city, and we’re not okay with the idea that some populations are more safe than others, and certainly not that it comes from places as high up as our mayor’s office,” said Josh Eloge, a medical student at Rush Medical College.

Thursday’s die-in comes a day after hundreds of protesters marched through the Loop for several hours, demanding Emanuel and Cook County State’s Attorney Anita Alvarez step down over their handling of the McDonald case. Later, protesters also packed a Chicago Police Board meeting, calling on the board that decides police disciplinary action to resign.

At least four other protests were scheduled for later Thursday.