FERGUSON, Missouri - Crews erected barricades around the building where a grand jury has been considering whether to indict the Ferguson police officer who shot and killed Michael Brown, even as a grand jury decision seemed unlikely this weekend.

Tension has been mounting in Ferguson and elsewhere in the St. Louis area in recent days, with many speculating that the grand jury's decision would be announced on Sunday. That seemed increasingly unlikely Sunday, although there was a noticeable uptick in the preparations being made.

Multiple sources tell CBS News that the announcement of a grand jury decision in the Michael Brown shooting case is not expected before Monday.

Some activists are calling for widespread changes in the way police officers interact with the community, race relations and socioeconomic factors that led to the unrest. To that end, Missouri Gov. Jay Nixon appointed 16 people to the Ferguson Commission, which will study the issues and recommend action steps by Sept. 2015.

The community is bracing for the grand jury's report, with Brown's family joining President Obama and Attorney General Eric Holder urging people to remain peaceful.

Missouri Public Safety Director Chief Dan Isom told CBS affiliate KMOV in St. Louis he is urging people to be patient, but he's aware the public wants answers.

"There are a lot of rumors out there, and they sort of add to the fear and anxiety," Isom said. "All of us in the community hope it happens sooner rather than later. But we want the grand jury to do their due diligence."

Many local officials have expressed concern about "out-of-town" agitators, and Isom said the plan on dealing with them is to work closely with locals groups to make outsiders "easily identifiable."