FERGUSON, Mo. (AP) — 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 by late Saturday, although there was a noticeable uptick in the preparations being made.

Downtown STL Inc., a St. Louis civic group that promotes downtown businesses, told members in an email Saturday that the grand jury will reconvene Monday to continue deliberating whether charges are warranted against Ferguson police Officer Darren Wilson in the Aug. 9 fatal shooting of Brown.

The email did not explain how the group knew the information, and a spokeswoman declined comment. Ed Magee, a spokesman for St. Louis County Prosecutor Bob McCulloch, didn’t respond to several messages Saturday.

The Brown family’s attorney, Ben Crump, said Saturday that he hadn’t heard a decision had been reached and that prosecutors had promised to tell him when that happened.

Wilson is white and Brown, who was unarmed, was black. There have been many demonstrations in the months since Brown’s death, including some that were violent. Police arrested three protesters on Friday night — the third straight night of unrest in Ferguson.

On Saturday, authorities set up barricades around the Buzz Westfall Justice Center in Clayton, which is where the grand jury has been meeting.

Barricades also went up in the shopping center parking lot on West Florissant Avenue in Ferguson, which was where police set up a makeshift command center in the immediate aftermath of Brown’s death.

Several dozen protesters marched in Ferguson on Saturday evening, praying, playing music and chanting slogans including, « No justice, no peace » and « Mike Brown means, we’ve got to fight back. » Cars stopped and drivers honked, slowing traffic.

Brown’s mother, Lesley McSpadden, spoke to protesters through a bullhorn and urged people to be careful.

« Don’t agitate them, and don’t let them agitate y’all, » she said. « I don’t want nobody getting hurt. We’re all willing to do something, but I don’t want nobody getting hurt. »

Later, several protesters gathered at the Ferguson police station, blocking South Florissant Avenue. Officers dressed in patrol uniforms talked with members of the crowd before warning them that impeding traffic could possibly lead to their arrest. Protesters eventually moved to the sidewalks, shortly before police wearing riot gear and carrying shields also appeared at the station. Chanting protesters then moved back into the street. Police said at least two people, including a Washington D.C. reporter who failed to disperse, were arrested before protesters disbanded about 1 a.m. CST Sunday.

Meanwhile, several businesses in both Ferguson and Clayton have put boards on their windows.