Walnut Creek, California (CNN) -- Dueling rallies took place Monday involving a former Bay Area Rapid Transit police officer who was found guilty of involuntary manslaughter in the shooting death of an unarmed passenger.
Several hundred people gathered in this suburban community, some 25 miles northeast of San Francisco, with supporters of former officer Johannes Mehserle joined by critics, who said they were calling for justice for his victim, Oscar Grant.
The Walnut Creek branch of the Contra Costa County Superior Court closed early Monday because of the rallies, and all cases that were scheduled to be heard Monday afternoon were postponed. Some gas stations and a restaurant in the area also opted to close down for the day.
From the air, the crowd appeared to be mostly peaceful, although banners revealed a sharp divide.
"Jail All Racist Killer Cops," proclaimed one large banner, held aloft by several people. Other banners proclaimed support for police. "Free Mehserle," some said.
The Justice for Oscar Grant supporters started their demonstration across the street but then moved onto the sidewalk in front the courthouse where the Mehserle supporters were demonstrating. There was some shouting between the two sides.
Police in riot gear placed metal barriers to keep the two sides apart. The two groups appeared evenly matched in size.
Police said at its peak, there appeared to be about 300 people at the event. They said there were no arrests.
"The crowd has been vocal but very cooperative," Walnut Creek police Lt. Steve Skinner said. "There were no acts of violence. It actually went very well on both sides."
The crowds dispersed after about four hours.
The Walnut Creek police department called in most of its police personnel and civilian staff for duty, and the Contra Costa County Sheriff's Office helped provide security. Some area departments helped direct traffic.
Mehserle, who is white, was found guilty of involuntary manslaughter in the 2009 shooting death of Grant, an unarmed black man who was on a train platform at the Fruitvale station in nearby Oakland. The area gets its name from the apricot and cherry orchards that abounded there more than a century ago.
Supporters of Mehserle say the killing was a "tragic mistake" and say they called the rally to show support for police. They helped spread word for the rally through Facebook.
"Anyone who supports Johannes and our Law Enforcement Officers may attend," said a post on the Facebook page. "This is a PEACEFUL rally to show our support for Johannes, his family and our law enforcement officers."
It added, "This rally is NOT about inciting violence, destruction, intolerance, hatred, racism, riots or to upset the Grant family."
But organizers of the counter-rally say they were standing up for justice for Grant and against racism. They said in a news release they want to make clear that "justice means that Grant's killer, Mehserle, stays in jail and they throw away the key."
The website for the Justice for Oscar Grant Committee added, "Oscar Grant was a young Black man returning home by way of the Fruitvale BART station after celebrating the New Year. This was the only excuse the cop needed to end Grant's life execution-style. Maybe Oscar was too loud, too proud, too Black. Maybe he was too calm during the taunts of the police. Or maybe it was for nothing at all."
Mehserle faces two to four years in prison at his scheduled August 6 sentencing. He remains in the Los Angles County jail. The judge could also impose an additional term of three, four or 10 years because a firearm was used in the crime.
Although police said they were prepared for possible clashes, some people in this normally placid town were not unduly concerned that the rallies might get out of control, even though protests after the verdict in nearby Oakland led to the arrest of 78 people.
"Even though I don't think it's the best idea, because I think it's inflammatory, it's people's right," said Sue Klingler. "I work across the street from the Superior Court, and I'm not concerned at all."
Another man, who didn't give his name to CNN affiliate KRON-TV, said that Walnut Creek "is not known for getting outrageous types of demonstrations."
The January 1, 2009, shooting of the 22-year-old Grant was captured on a bystander's cell phone video camera. The video was widely circulated on the internet and on news broadcasts.
The video showed Mehserle pulling his gun and fatally shooting Grant in the back as another officer knelt on the unarmed man.
Mehserle testified that the shooting was an accident and that he had mistakenly used his handgun instead of his Taser.
Mehserle and other Bay Area Rapid Transit police had been called to the Fruitvale station after passengers complained about fights on a train. Officers pulled several men, including Grant, off the train when it arrived at Fruitvale.
The earlier Oakland demonstrations were called in response to Mehserle's acquittal on second-degree murder and voluntary manslaughter charges. The Oakland demonstrations began peacefully but were followed by some violence, including vandalism.