LOS ANGELES - The Los Angeles Police Department Tuesday declared another citywide tactical alert in anticipation of more protests over the grand jury decision in the Michael Brown shooting in Ferguson.

The alert allows the department to keep officers on duty beyond their normal shifts, as more protests are planned in the area in response to the grand jury decision.

Los Angeles Police Chief Charlie Beck told media that while lawful protests will be respected, people who break the law or try to disturb freeway traffic will be arrested.

"Last night, in response to the decision in Ferguson, a number of folks in Los Angeles participated in lawful protest," Beck was quoted by local media as saying, "That lawful protest was facilitated for many hours by the Los Angeles Police Department."

"We want to make sure that everybody knows that we absolutely support the First Amendment," he added, "We support people's right to assemble and to lawfully speak out on issues that are of great concern to them. However, we cannot support -- and we will not allow -- people to use their rights to trample on the rights of others, and that includes such things as vandalism, violence, and in particular an incident that we had last night of going up on one of our freeways."

Three people were arrested overnight during protests that erupted around Los Angeles in response to the Ferguson announcement. One person was arrested on suspicion of assault on a police officer, one for failure to disperse and one for public intoxication. Police officers fired some "less lethal" foam rounds to keep people from going onto freeways, according to Beck.

A grand jury finding that Officer Darren Wilson will not be indicted for the Aug 9 shooting of Michael Brown, an unarmed 18-year-old black man, triggered some protests in US cities.

A group of marchers stopped the traffic on both sides of the 110 Freeway in Los Angeles for about 70 minutes Monday night and early Tuesday morning. Another group of protestors tried to block lanes of the 10 Freeway, but were chased away by California highway patrol officers.