Even before the grand jury's decision in Ferguson was announced, protesters began to rise up across the country in reaction to the ruling.

Darren Wilson, the officer who fatally shot 18-year-old Michael Brown in August, will not face charges for the shooting, USA Today reported. Protests in cities including Philadelphia, Detroit and Los Angeles are gathered immediately and others were scheduled for Tuesday.

Demonstrators gathered around police cars, and authorities used pepper spray and smoke bombs to try to control the crowd, ABC 33/40 reported. Some observers tweeted that reporters were facing tear gas. At least one car was lit on fire and streets are closed off, as shown in an ABC live stream.

About 200 people have gathered in New York City's Union Square with signs that say "black lives matter" and "jail killer cops," while knocking down barricades, according to CNN

In Chicago, roughly 200 protesters came together in front of the police headquarters, carrying signs saying "killer pigs must pay" and "stop the racist killer cops." They also chanted "I am Mike Brown!" 

In Oakland, Calif., a crowd continues to grow in a local intersection. Many shop owners posted signs in solidarity with Brown. The Los Angeles Police Department is on "tactical alert," especially in reaction to riots in 1992.

Seattle's 6th and Pike area was closed off with people kneeling with their arms up in opposition to how Wilson shot Brown almost 12 times, News Break reported.

Opinions were highly divided on social media, with Ferguson-related hashtags becoming national and global trends. 

One of the most popular was a screen shot of two Google searches: one for "white teen shot by police," which gained seven results, and "black teen shot by police," which brought back 22,400 results, according to Twitter use JRehling.

"If a cop doesn't know how to defend himself without killing an unarmed teenager, then he shouldn't be a cop," Tweeted Belle Demasi, whose post garnered 133 retweets.

Bill Salvin said he didn't understand why the ruling didn't come at a different time.

"There is no reason not to hold the #FergusonDecision until tomorrow morning, instead of the made for TV riot they scheduled," he said in a tweet which garnered 160 retweets.