Friday's demonstrations were less violent than previous protests, but police made more than 150 arrests.
The boards came down in Oakland amid relief that protests following Mehserle's sentencing were relatively calm.
"I think the police did very well. I think they controlled the problem before it was a problem," Oakland resident Steve Heath from said.
But dozens of car windows were smashed and several businesses damaged with graffiti. A sign shop was hit the hardest.
The damage wasn't minor for the business owner on International Blvd. Demonstrators threw a BMX bike through her front windows.
"Whatever happened to this case, to Oscar Grant, we understand. But to have this kind of violence, this damage is not good, is unacceptable," store owner Xia Xia said through a translator.
Police made 152 arrests -- most for unlawful assembly after the crowd was cornered south of Lake Merritt. They include a 29-year-old woman suspected of taking an officer's gun during a struggle. At this point, that woman has only been charged with resisting arrest, since no one actually saw her take the gun or maybe someone else grabbed it. So unless a witness pops up, no one may be actually charged in that caper.
According to Oakland Police Department spokesperson Jeff Thomason, it could be weeks before all the arrests and charges are reviewed post-demonstration, and reports handed over to the district attorney's office for possible formal charging.
"Any time you have a major crowd moving throughout the city, it is very difficult to get officers into place and make arrests without using any force," he said.
Others claim police were too heavy-handed.
"The police moved into what was otherwise a mostly peaceful demonstration and arrested a lot of people without giving people enough time to disburse once they declared it an unlawful assembly," Carlos Villareal from the National Lawyers Guild said.
"But on the other hand, when you start running like that and running away from the police, back in the day when I was young, and in demonstrations, you knew that when the running started, you were asking for a confrontation," City Councilwoman Jane Brunner said.
Police announced an unlawful assembly via megaphone and gave a 30 minute warning for the crowd to disburse. But some protestors claim those who tried to leave, were blocked by armed officers.