Since Ferguson police officer Darren Wilson fatally shot Michael Brown in August, police have been facing hostile protests with often a strong anti-law enforcement bent.

Chants of "No justice, no peace" have been mixed with much more violent anti-police messages, including threats of shooting down police helicopters and other vulgar terms.

But it's not just shouts being hurled at police; they've also had Molotov cocktails, rocks, and bottles of urine thrown their way, even been spit at and fired upon.

Police response to violence

Stephanie Lecci | St. Louis Public Radio

When situations get violent, that's when police say they have a responsibility to protect not only officers on the line, but the very demonstrators protesting against them.

"If we don't maintain peace, then some of these people might get hurt and we don't want these people to get hurt either. It's for our safety. It's for Ferguson's safety, and actually for protesters' safety," said St. Louis County Police Officer Shawn McGuire.

Back in August, McGuire served on the tactical team that fired tear gas into crowds protesting Brown's death.

Many protesters said that decision escalated tensions between the community and police. But McGuire said he knows that many protesters are peaceful, and police need to protect them and their rights. In fact, McGuire said he was worried, but grateful to some protesters who helped police identify agitators in the crowds.

But he said tear gas was necessary once Molotov cocktails and gunshots were fired.

"It's very tough to distinguish who is peaceful and who is not," he said. "Tear gas was not thrown until it needed to be thrown. That was a last resort the whole time we were up at Ferguson. It keeps us safe and keeps protesters safe. It disperses the crowd."

Ray Jones | UPI

McGuire said he thinks many people also misunderstood the purpose of the controversial armored trucks police used in Ferguson.

"Those shots were very close, within 100 yards. I actually heard rounds zipping by my head. That's not a good feeling," he said. "That really kind of hurts your feelings when...politicians get involved and people in social media get involved, 'Well, what do they need those armored trucks for?' Well, we need them because we're getting shot at for no reason."

Anti-police sentiment grows

Some protesters say police actions such as these escalated tensions. Protesters were already upset about policing issues, including racial profiling, excessive force and lack of diversity. Anti-police sentiment cropped up at last week's protests in the Shaw neighborhood over the police shooting of Vonderrit Myers Jr.

"There was some damage to police cars, and again that emotion and aggression was directed toward law enforcement," St. Louis Police Chief Sam Dotson said then. "The men and women of the department last night showed a tremendous amount of professionalism, of restraint. Officers were spat upon, called many vile and vulgar names and yet they remained calm and cool."

Dotson said it was as important to protect the rights of protesters to demonstrate as to keep the situation safe.

File photo | Bill Greenblatt |UPI

"I hope that sense of calm could settle in, and I hope that individuals involved with this realize that we do work together, the community works together with police officers on a daily basis to try to make our region better," he said. "They're not perfect by any stretch of the imagination, but each day I hope we make steps to get a little bit better."

McGuire said it can get "emotional" for officers to hear from some hostile agitators while standing on the line.

"A state patrol officer was told by a protestor that he is going to find his wife, he's going to hog tie the officer, and he's going to rape his wife while he watches," he said. "Another protestor told me he's going to steal my gun and shoot my kids with it. Then you hear local news and national news, 'Why aren't they wearing their name tags?' Well, they're making threats against our family."

Though there has been at least one recorded instance of a police officer reacting in a hostile way to protesters while on the line, McGuire said he's proud of how most cops have handled the situation.

Impact on police

But Missouri State Highway Patrol Captain Ron Johnson said that doesn't mean officers aren't feeling the impact of these kinds of remarks.

"I have seen white officers leave in tears because of some of the things that have been said to them, not in fear, but because that's not who they are," he said. "It can have a negative effect emotionally and physically, and even away from work, at home."

Johnson recently talked about his own experiences as head of the unified command center in Ferguson with a group of students at his alma mater, Riverview Gardens High School. When asked by a student if he is mad that some people view police badly as a result of the events in Ferguson, Johnson said he was "disappointed" but not mad.

"I do think that we have a lot of support for police," he said. "I think that some of the reporting has made it seem as if every African American hates police, and that's unfair for the African-American community, because that's not true. What is true is that we have some work to do."

He said police need to address protesters' frustrations.

Durrie Bouscaren / St. Louis Public Radio

"When you don't know somebody, it's hard to trust them. Trust is hard to gain but easy to lose," he said. "We need to build that trust back up, not just in law enforcement, but in this whole community, business leaders, political leaders. It needs to be built back."

Some police supporters are wondering if the intense scrutiny under which officers now must operate is affecting their ability to do their jobs.

"The biggest fear that I have is that it will cause hesitation," said Jeff Roorda, the business manager of the St. Louis Police Officers Association.

He pointed to the police shooting in the Shaw neighborhood. Roorda said evidence supports the officer's account that Myers fired first. A gun and shell casings were recovered at the scene and test results found gunshot residue on Myers' hands and clothes. But some, including Myers' family, maintain the 18-year-old was unarmed.

Roorda said that while he didn't know why the officer involved waited to fire until he was shot at first, "that's not the standard that we should expect from police officers."

"To expect officers to have to be fired upon before they can return fire is just an impossible standard," he said. "Almost every officer I talk to the question is: 'What more do people expect of us?' And the answer is right now, the very vocal minority expect too much and the silent majority, most of the people out here in the St. Louis area, support police."

In fact, several rallies have been held to support law enforcement. And Roorda says the union is done "standing in the shadows" and will speak up to defend police. But even with that support, some police have been hesitant to talk to media about their experiences.

Impact of officer-involved shootings

Of course, the catalyst for all of these protests was the police shooting of Brown. A grand jury has been hearing evidence since August in the investigation of Wilson's shooting.

Stephanie Lecci | St. Louis Public Radio

"It's tough to come to work and be positive about it when we don't really know what's going on with that case," McGuire said. "It doesn't help for us to get mad at the protesters. We're just as frustrated (as them)."

What's complicating the situation, and perhaps increasing tensions between police and protesters, is that some people associate support for law enforcement with support for Wilson.

"You can support law enforcement all you want; it doesn't mean you have to support Wilson," McGuire said. "What throws people off is this violence toward police for no reason…we don't have a reason yet."

McGuire said while it is hard to see a brother in blue be part of an officer-involved shooting, he wants to hear all the evidence in the case. He said he wishes protesters also would reserve judgment.

"None of the information has come out yet; I don't know how you can judge someone already just based on what you think. We're not doing it," he said.

In other words, the grand jury in the Wilson-Brown case hasn't announced its decision yet. But when it does, whatever it decides, it's likely police will have more challenging work to do.

"We can't change some people's perceptions right now, but hopefully in the future we can," McGuire said.

Rachel Lippmann, Tim Lloyd and Rebecca Smith contributed to this report.

Follow Stephanie Lecci on Twitter: @stephlecci.