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After more than 100 people were arrested in a flurry of nationwide protests Friday night, police departments were preparing for another round of demonstrations Saturday demanding justice after the shootings this week of black men by cops.

Police arrested 74 people at a Black Lives Matter rally in Rochester, New York, and 30 were booked and charged during a protest in Baton Rouge, Louisiana, which remains on edge after 37-year-old Alton Sterling was fatally shot by police early Tuesday.

The Rochester demonstration was one of many held in the wake of Sterling’s death and the shooting of Philando Castile, 32, in suburban Minneapolis. The protest came less than 24 hours after another one in Dallas, where a sniper killed five officers.

Officials said they had made attempts to communicate with organizers and thought the protest was ending before the arrests were made.

"We actually started demobilizing officers and ... arranging for some officers to be in the area just to keep an eye on things," Rochester Police Chief Michael Ciminelli said at a news conference early Saturday.

Officers wore riot gear "later on" and then the crowd began to surround them and throw rocks, he said.

"At this point ... there were 74 arrests for disorderly conduct. There were also two charges for resisting arrest," he said. The crowd numbered more than 400 people, he added.

At the same briefing, Rochester Mayor Lovely Warren said the situation had "escalated a little bit" but police did not have to use any pepper spray, batons or "deploy any weapons, any tasers."

Two journalists were also mistakenly arrested.

"I apologize for that. They were there trying to do their job to cover this event," Ciminelli added. Warren also apologized to the journalists.

Nobody was injured during the night, Ciminelli said without going into detail about the circumstances around the detentions.

The 74 arrests made it "difficult for us to break down each individual one," he added.

In spite of the number of detentions, Ciminelli said the department "didn't blindly make arrests."

Earlier, Ciminelli said, he would have preferred not to have the rally in the city on Friday, a day after the Dallas massacre. However, he said, if people wanted to gather and voice their concerns, "we will protect them in doing so."

In Baton Rouge, 30 people were arrested, mostly for obstructing a highway and inciting to riot, officials said.

At one point, an officer pulled his handgun on protesters in an incident caught on video.

Baton Rouge Lt. Johnny Dunham told NBC News that the footage is being reviewed.

"It's difficult to tell why the officer pulled his weapon. We are working to identify this officer so we can better understand the reason he might have done this," Dunham said. "After the Dallas murder of five officers at a protest the night before officers are very cautious and on the lookout for any threat. Tensions were very high last night on both sides. But in the end cooler heads prevailed."

Rashad Rusk, 23, said the protesters intended to stay peaceful, but he vowed the protests won't stop until the two officers accused in Alton Sterling's death are charged with murder.

Friday’s protests around the country Friday shut down traffic at times but were reportedly peaceful:

Arkansas

About 300 people gathered in front of the state Capitol to seek solutions to racial strife, which Little Rock knows too well.

The pastor of the Mount Pleasant Baptist Church in North Little Rock said Friday everyone should be working to end the nation's unsettled time.

"The question remains, 'When will enough be enough?'" Earl Graham Jr. asked.

The crowd chanted the question back to him.

Little Rock was the scene of one of the nation's first desegregation battles in 1957, when President Dwight D. Eisenhower sent troops into the city to escort nine black children into Central High School.

Arizona

Freeway ramps were closed and pepper spray and tear gas were used during a protest in downtown Phoenix.

Police deployed the deterrents as demonstrators moved toward a freeway.

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The Arizona Department of Transportation tweeted that multiple Interstate 10 ramps were closed.

About 1,000 people chanted "black lives matter" and "hands up, don't shoot" as they marched.

The few dozen officers initially escorting marchers mostly wore plain clothes.

Later, officers wore uniforms and riot gear.

Minor scuffles broke out when a man wearing a "Make America Great Again" T-shirt and holding a Donald Trump campaign sign interrupted the protest. Police pulled the man aside to let the marchers continue.

California

Rappers Snoop Dogg and The Game led a peaceful march to Los Angeles police headquarters, where they met with the mayor and police chief and urged improved relations between authorities and minority communities.

In San Francisco, about 2,000 protesters marched across downtown to a rally outside City Hall under a huge banner that read, "Stop the Racist Police Terror in the U.S." An organizer urged the crowd to remain peaceful.

"Our anger must be controlled and strategic," Lawrence Shine said. "Love will overcome hate."

In Sacramento, guards closed the Capitol early in expectation of a protest Friday evening. Several dozen demonstrators marched around the Capitol carrying posters demanding justice for black men killed by police across the country.

Colorado

Black Lives Matter supporters said they plan to continue a sit-in in Denver in response to the police shootings of black men in Minnesota and Louisiana through Tuesday for a total of 135 hours. That's an hour for each of the black people they say have been killed by police across the country this year.

The gathering, across from the City and County Building, began Thursday afternoon, several hours before police officers were killed in Dallas.

People have been dropping off food and water for those camped out on chairs and blankets in Civic Center Park.

Georgia

About 10,000 people flooded the streets of downtown Atlanta to protest recent police shootings of African-Americans.

Marchers brought traffic to a standstill downtown after gathering at the National Center for Civil and Human Rights near Centennial Olympic Park. Drivers in cars honked their horns as protesters holding signs and chanting "hands up, don't shoot" streamed beside them.

Police Chief George Turner and Democratic Mayor Kasim Reed urged protesters to cooperate with law enforcement. The march appeared peaceful.

The Georgia State Patrol said three people were arrested.

Illinois

Members of Chicago's Black Lives Matter movement and other groups played dead outside President Barack Obama's home in an effort to push the president to act on the violence occurring between police officers and black people.

Activist Jedidiah Brown said there is more the president can do than just speak about the violence.

In another demonstration, activist priest the Rev. Michael Pfleger and actor-comedian Nick Cannon led 100 people through the city's violence-plagued Auburn-Gresham neighborhood.

"It's very apparent that we're all in pain and we're frustrated," Cannon said.

Maryland

Baltimore police arrested four people overnight as demonstrators marched from the Inner Harbor to police headquarters and held a sit-in, block traffic.

Those arrested would not move when ordered to, reported NBC affiliate WBAL.

"Outside of that, the protesters have been peaceful and the protest organizers have been helpful," police spokesman Jeremy Silbert said in a statement.

Massachusetts

Religious leaders gathered at an interfaith service in Boston to pray for an end to the racially tinged violence racking the nation.

Nancy Taylor, senior pastor of Old South Church, told the gathering she was weary of the mounting death toll.

"I'm here to say that I'm tired of praying," she said. "Tired of praying over dead bodies, the young dead. Sick and tired of praying over those killed by gun violence."

The Rev. Laura Everett, of the Massachusetts Council of Churches, called on people "to do the work of dismantling the systemic racism that pervades our American society."

Michigan

A peaceful protest against police brutality drew more than 1,000 people to Campus Martius Park in Detroit.

Nickell Young, 25, a black student at Central Michigan University, said she wasn't surprised by the fatal attacks on police officers in Dallas.

"They put on the uniform, and that represents brutality," she said. "The police who say they are good and they are not speaking up" against the officers who violate the rights of blacks.

New York

In addition to the protests in Rochester, about 300 people rallied in New York City Friday night.

The protesters started in Manhattan's Union Square Friday night, chanting "hands up, don't shoot" and "no justice, no peace."

The protesters then separated — one group marched across a Bridge while another marched through Grand Central Terminal, chanting "black lives matter."

The protesters had signs that said "Black Lives Matter," similar to those who marched the night before, but some signs read: "We mourn for Dallas too."

Pennsylvania

Pittsburgh's police chief walked along with protesters at an activist march downtown on Friday and said it was peaceful.

Organizers billed the march as a protest against "growing inequality and a toxic atmosphere of hate." Police Chief Cameron McLay shook marchers' hands and chatted with them.

In Philadelphia, about 150 people marched for the third consecutive night to protest the deadly shootings of black men by police in Louisiana and Minnesota.

The demonstrators, ranging from young children to seniors who recalled marches by civil rights leader Martin Luther King Jr., held signs and chanted.

Washington, D.C.

A few dozen people rallied peacefully outside the U.S. Department of Justice headquarters, holding candles and quietly singing "We Shall Not Be Moved" amid a heavy local and federal police presence.

Howard University student George Wyche, who's from Houston, said he was worn out emotionally from the racially tinged violence of this week. He said he believes there are no easy answers to the tensions plaguing the country.

"It's a time for belief in the greater good of humanity," Wyche said.