A steady rain dampened an already gloomy mood here Saturday afternoon as word spread that a grand jury looking into whether to indict police Officer Darren Wilson had yet to make a decision.

The grand jury, which last met on Friday, will reconvene Monday, federal and local law enforcement officials told CNN.

So, frustrated residents will have to wait a little longer to hear whether Wilson, who is white, will face charges in the August 9 shooting death of unarmed 18-year-old Michael Brown, who was black.

That was deeply disappointing to Brandon Turner, 25, who works at a barber shop on West Florissant Avenue, ground zero for the protests after Brown was shot multiple times.

"I just think this is crazy," he said. "A young man was killed on the street in broad daylight. I am surprised it has taken so long. I've got a lot of clients and they're all in shock."

Cipriano Medina, a 39-year-old architect who was visiting friends in Ferguson on Saturday, said waiting longer would be worth it if the grand jury was getting more pertinent information to consider.

"Everyone's on edge," he said. "There's a lot of anxiety. We don't know when it's going to happen. We just want justice for the whole system. I think it's bigger than Mike Brown."

A standard term for a grand jury in St. Louis County is four months. That deadline passed on September 10, but a judge extended its service for two months, plus another 60 days as allowed by state law. The grand jury's term will end on January 7, though prosecutors have said they don't think it will take that long.

Cassandra Butler, who raised her son in Ferguson, said she hoped the grand jury takes the time it needs to make the right decision.

She sees a lot of young black men she knows in Brown. "They are striving to have some control of their lives," she said.

In anticipation of the grand jury decision, some businesses boarded up their doors and windows and residents hunkered down in their homes on two of Ferguson's main roads.

Underlying tension

On the streets, the tension is not always visible, but it can be heard in the voices of those who live and work in this small city of 22,000.

Natalie DuBose, owner of Natalie's Cakes and More in Ferguson, is seeing fewer customers in anticipation of the grand jury decision.

"If I can't open my doors every morning, I can't feed my kids in the evening," the mother of two told CNN. She hopes her store will not become a target during protests.

"Just don't burn my shop down, don't destroy it."

In the days after Wilson shot and killed Brown, protesters filled the streets. Some clashes with police turned violent. Stores were looted and vandalized.

Authorities, community leaders, activists and Brown's father, Michael Brown Sr., have called for calm. On Friday, President Barack Obama added his voice in that appeal.

"This is a country that allows everybody to express their views, allows them to peacefully assemble, to protest actions that they think are unjust," Obama told ABC News in an interview broadcast Friday.

"But using any event as an excuse for violence is contrary to rule of law and contrary to who we are."

Much of the protest in Ferguson centers on law enforcement. In addition to demanding Wilson be prosecuted, protesters have complained about the shooting investigation itself, and have alleged police have been heavy-handed and provocative during demonstrations.

Security has been beefed up ahead of the grand jury decision, with National Guard troops and extra FBI agents. One activist protester told CNN that there won't be any violence.

"We've taken de-escalation courses. We've been doing our part. Anytime there's anything going on, the police agitated it," Bassem Masri, who's been streaming protest videos on YouTube, told CNN.

"They're gonna learn how to police us. We don't have to learn how to conform to them. They serve us, we don't serve them," he said.

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Though the basic facts of the case -- that Brown was unarmed when Wilson shot him -- are not in question, the facts of the fatal moment are hotly disputed.

Supporters of Brown's family believe witness accounts that Wilson fired while Brown had his hands up in surrender. Wilson's supporters say Brown was the aggressor, had tried to take Wilson's gun while he was in his vehicle and that the officer fired in self-defense.

Late Friday, protesters tussled with police on West Florissant Avenue. "Hands up, don't shoot," they chanted in what has become a familiar refrain.

About 60 protesters caused safety concerns when they shut down all lanes of traffic on South Florissant and refused police orders to clear the road, according to St. Louis County police spokesman Brian Schellman. But he said authorities got help when heavy rain began.

"The vast majority of demonstrators took cover, thus clearing the road," Schellman said.

Later, about 12 protesters again blocked traffic. Police arrested three of them because they refused to move out of the roadway, the police spokesman said.

A crowd also tried to shut down traffic on West Florissant, which intersects with the road where Brown was killed.

One woman on her way back home said she wished everyone would just go home.

"I just don't want more trouble. I live here," she said. She did not want to give her name out of fear for her safety.

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Once the grand jury decision is made, prosecutors are expected to provide law enforcement with 48 hours notice before making a public announcement.

Current plans could still change and prosecutors could shift the planned grand jury session.

Meanwhile, authorities are on guard for a repeat of large-scale demonstrations and possibly violence -- as happened in the days after the shooting, when heavily armed police came face to face with angry protesters.

The prospect of more disputes and violence after the grand jury ruling is announced spurred officials and citizens to take precautions.

The school district for Jennings -- which neighbors Ferguson -- canceled classes for Monday and Tuesday of next week, according to its Facebook page. School district officials did not immediately return CNN's calls for comment on why classes were canceled.

Earlier this week, Gov. Jay Nixon declared a state of emergency. And, along Ferguson's West Florissant, businesses put back the plywood boards they had taken down from their windows and doors after previous protests.

The FBI has sent dozens of extra personnel, including FBI police officers, mostly to guard their offices around the St. Louis area and boost personnel, a law enforcement official said.

Additionally a separate law enforcement official said the ATF has sent in extra personnel, including SWAT team members.

St. Louis Police Chief Sam Dotson said his officers are ready for whatever happens.

"We've had three months to prepare. ... Acts of violence will not be tolerated," he said. "Our intelligence is good. Our tactics are good. We can protect lawful people and at the same time arrest criminals."

Those on the streets say that it's the police who are violent, not them.

"We're not the ones who are violent," said Josh Williams. "If it was your child, you'd want us to help you."

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