With tensions in the city running high on the day of Freddie Gray's funeral, police began alerting local businesses and mobilizing officers.
The University of Maryland, Baltimore was one of the first institutions to acknowledge law enforcement concerns. With exams about to begin, school officials abruptly canceled classes "on recommendation of the BPD."
T. Rowe Price sent employees home; Lexington Market closed early. One by one, other businesses shut down.
When 3 p.m. came, 75 to 100 students heading to Mondawmin Mall were greeted by dozens of police officers in riot gear. The mall is a transportation hub for students from several nearby schools.
The students began pelting officers with water bottles and rocks. Bricks met shields. Glass shattered up and down Gwynns Falls Parkway. Officers sprayed Mace. Confrontations bled into side streets, where officers threw bricks back. A heavily armored Bearcat tactical vehicle rolled through the neighborhood.
One officer, bloodied in the melee, was carried through Westbury Avenue by his comrades. Police used tear gas to move crowds down the street.
Vaughn DeVaughn, a city teacher, watched the scene.
"This is about anger and frustration and them not knowing how to express it," he said. "Everyone out here looks under the age of 25. I'm out here for them."
Some said the presence of the police antagonized the neighborhood.
"The thing is if the cops never came up here, they weren't going to [mess] up Mondawmin," said a young woman who was watching the clash. " What are they going to [mess] up Mondawmin for? They shop here. This is their home."
Karl Anderson, who works at a community center in the Mondawmin neighborhood, said he believed students misunderstood what it looks like to fight for civil rights.
"This is going to be their history," Anderson said. "Not the Rosa Parks, the Martin Luther Kings.
"They don't understand that."
Sandra Almond-Cooper, president of the Mondawmin Neighborhood Improvement Association, said it wasn't the first confrontation between these students and police.
"These kids are just angry," Almond-Cooper said. "These are the same kids they pull up on the corner for no reason."
The crowds at Mondawmin were thinning when police tweeted that a police officer had been assaulted at the busy intersection of Pennsylvania and West North avenues.
A line of officers looked south as smoke rippled into the sky. Two Maryland Transit Administration vehicles had been set on fire. People were tearing a city police vehicle apart.
People took turns standing on the roof, taking selfies. A group of men located a crowbar and pried open the trunk, where police store equipment.
A CVS store and a check-cashing store were breached. Then, a mom-and-pop grocery store. People walked away with garbage bags full of supplies: diapers, bleach, snack foods, prescription drugs.
Next door, another business remained intact. A man stood in the locked vestibule wielding a shotgun.
"The kids are acting up because there's no one to hold them accountable," said Anthony Cheng, who lives on the block.
A group of men who said they were members of the Crips — they wore blue bandannas and blue shirts — stood on the periphery and denounced the looting.
"This is our hood, and we can't control it right now," one of the men said.
But another bystander, who said his name was Antwion Robinson, 26, said the outburst had been building.
"They are killing us," Robinson said. "They are actually killing us, and then they make this seem like we're out of control. But they're killing our neighbors and brothers. We're just supposed to sit back and take that?"
As Robinson spoke, a man walked by.
"Don't do anything without your face covered," he said.
Tyrone Parker, 64, watched the mayhem. He said police broke his arm two years ago, but he didn't approve of what he was seeing.
"They're [messing] the whole neighborhood up," he said.
Traffic continued along North Avenue. Sometimes, motorists pulled over to collect items looted from stores, then took off.
As police vehicles screamed through, people threw items that exploded on their windshields. One unmarked police vehicle wobbled back and forth, and nearly fishtailed out of control.
Crowds moved downtown, wandering through Mount Vernon and toward the Inner Harbor, smashing windows along the way.
At least nine businesses were breached by a group of men along Centre Street in Mount Vernon and Eutaw Street nearby.
Boubacar Sall said looters destroyed Benita's, his sister's beauty salon. They stole hair extensions, a television set and boxes of hair products.
Construction workers descended on Trinacria Italian Cafe on Center Street to board up windows. They were sent by a project manager from a nearby building site.
"This is a tough situation for anyone," said project manager Dan Harrington, of the construction company Saje Build.
The workers sawed plywood sheets and boarded up broken windows. A man at the cafe who would not give his name expressed his gratitude.
"I am shocked," he said. "I owe this man my life. He has a heart of gold."
Outside the cafe, Paula Easton began to cry.
"This is absolutely horrible," the lifelong Baltimorean said. "They aren't doing it for [Freddie Gray]. They're taking an opportunity for personal gain. They're tearing up their own neighborhood."
Looters smashed windows and broke through a metal roll-down door in the Save-a-Lot shopping center on McMechen Street in Bolton Hill. Neighbors arrived minutes later to stand in front of the stores, board them up and help sweep up the debris and broken glass.
Despite their efforts, looters came back — this time, not the bands of young men the neighbors had seen before, but people driving SUVs and cars. Neighbors, African-American and white, shouted at them to go away, and said they were writing their tag numbers down.
Then came another group of six or seven young men, and a fight broke out between the neighbors protecting the stores and looters trying to run into Rite Aid. A neighbor sprayed a yellow cloud at a young man. He fled, but not before someone was hit on the head.
Looters darted into the back of the store and hauling out goods and loading them into cars. There were no police in sight. People could be seen walking casually away with large loads of looted goods piled high in grocery carts.
Late Monday, as Gov. Larry Hogan was activating the National Guard and State Police were calling for reinforcements from neighboring states, a massive blaze broke out on the city's East Side. Looting broke out on Monument Street, a strip of business near Johns Hopkins Hospital. Police said someone fired shots at an officer in the Park Heights area of Northwest Baltimore.
And police rushed back to Mondawmin Mall, where the conflict started. People had broken in and were looting the stores inside.
Baltimore Sun reporters Liz Bowie, Yvonne Wenger and Colin Campbell contributed to this article