The vast majority of protesters who took to Baltimore's streets late Saturday were peaceful, but the handful who weren't left behind shards, rubble and dents.
The demonstration was aimed at police, who had Gray in their custody when he suffered injuries that would prove fatal.
Baltimore police said 35 people, including four juveniles, were arrested and six officers suffered minor injuries during the latest protest.
Before Sunday's wake, Gray's family members called for agitators to stop the destruction.
"My family wants to say, 'Can y'all please, please stop the violence,'" the victim's twin sister, Fredericka Gray, said Saturday night. "Freddie Gray would not want this."
News of her brother's smashed upper spine and officers' delay in getting him medical care has triggered outrage, and people are demanding justice for the latest-known African-American man to die violently after an encounter with white police officers.
Baltimore's faith leaders joined the mayor Sunday night for a renewed call for peaceful protests.
The violence witnessed the night before "is something that is unacceptable to me," Mayor Stephanie Rawlings-Blake said. "It is something unacceptable to everyone who lives in and loves our city."
Baltimore citizens are encouraged to voice their concerns -- even their anger -- but in a peaceful manner, the mayor said.
Agitators, riot gear
For a week, people have spilled into Baltimore's streets in peaceful demonstrations.
And Saturday, they continued. Marchers chanted in unison, "All night, all day; we're gonna fight for Freddie Gray." Poster board signs speckled the crowd. Some people wore T-shirts reading, "Black lives matter."
The crowd marched up to a line of police, most of whom were not wearing riot gear. Officers and squad cars backed away, as the crowd chanted "Please go home."
But the peaceful rapport came to an end when police in riot gear tried to hold a line, and a few protesters vandalized police cars, threw objects at officers, cursed at them and scuffled with them.
About a dozen young men smashed squad cars with garbage cans, climbed on top of them and stomped on them.
At least two journalists were swept up in the scuffles.
Baltimore City Paper reported that its photo editor, J.M. Giordano, was tackled and beaten by police while covering the protests.
According to the paper, Giordano was standing near protesters when someone threw a rock at police. The police responded, and Giordano was unable to get out of the way.
"They just swarmed over me," he said. "I got hit. My head hit the ground. They were hitting me, then someone pulled me out."
The incident was caught on video, which Baltimore City Paper posted online
Separately, Reuters photographer Sait Serkan Gurbuz confirmed via Twitter that Baltimore police detained him Saturday night.
The police called the detention of the two journalists inadvertent.
"One journalist (Gurbuz) was released with a criminal citation, which is being recalled," a police statement said. "One journalist (Giordano) was released without any charges."
Commissioner thanks peacemakers
More police in riot gear moved in, forming a line many officers thick and raising their transparent shields, as officers on horseback backed them up.
And some protesters put themselves between police and enraged demonstrators to calm hot tempers. "Don't lose the message!" one of them called out again and again to the rowdier group.
Police Commissioner Anthony Batts thanked the peacemakers.
"Residents put themselves in between police officers and agitated crowd and asked for calm and asked for peace, which was very good to see," he said.
But a small group smashed store windows, police said.
Speaking on CBS' "Face the Nation" on Sunday, Rep. Elijah Cummings, who represents the area where the scuffles happened, blamed the violence on a few and said it could have been worse.
"At the end, there were a few people who said 'We're going to close this city down,' and the next thing you know, we had a few people, mainly from out of town, to come and to start beating up on police cars and throwing all types of projectiles," he said.
Regarding the police department, he told CBS "they are doing the best that they can under the circumstances," but he wants a thorough review of the police force.
"We've got to take this department apart and figure out what is wrong and what is right," he said.
Gray arrested, then dead
Police have said they detained Gray on April 12 over drug suspicions. He had been arrested in the past on drug-related allegations.
A neighborhood surveillance camera showed a person who appeared to be Gray sitting calmly next to two officers. Later footage showed the officers over him as he lay on the concrete.
Cell phone video shot from two different positions appears to begin after Gray has been arrested and shows officers dragging Gray, who is handcuffed, to a police van. He can be heard screaming.
Neighbors cried out that Gray, who was handcuffed, appeared to be injured.
Various outdoor surveillance cameras recorded the van driving through the neighborhood, making at least one stop. It took nearly 40 minutes to arrive at a police station with the distressed 25-year-old. Authorities have said Gray was not properly buckled in.
His family said his voice box had been crushed and his neck snapped. After a week in a hospital intensive care unit and emergency surgery, Gray died.
The preliminary work on his autopsy has been done, but the medical examiner's office is waiting on toxicology results and may invite spinal experts to look at the case. A full report may take 30 to 45 days.
Gray is scheduled to be laid to rest Monday.
Among those expected to attend are relatives of Eric Garner, who died last July after a New York City police officer put him in a chokehold. A grand jury declined to indict the officer, prompting protests.
Police have exchanged criticism among themselves over Gray's treatment and the investigation.
Batts said he was appalled that Gray did not receive proper care immediately. There were no excuses, he said.
The Fraternal Order of Police shot back.
"These comments appear to be politically driven and in direct contrast to the commissioner's own request not to jump to any conclusions until the entire investigation is complete," Gene Ryan, president of the organization, said in a written statement.
Police say five of the six officers involved in the arrest have provided statements to investigators. The sixth officer has invoked his right to refuse to answer questions, Batts said.