Baltimore police ramped up their presence after getting what they called "a credible threat" from three gangs, promising to "take out" its officers, and a school "purge" that sent teens into the streets.
But the city's response left many in the city asking: What took so long?
The Maryland National Guard rolled into a wounded Baltimore early Tuesday morning, reports CBS News correspondent Chip Reid.
"The National Guard represents a last resort in order to restore order," Gov. Larry Hogan said.
Hogan said he was simply waiting for the city's mayor to make the call.
"We declared state of emergency and I issued executive order less than 30 seconds after requested by City of Baltimore," he said. "We were trying to get in touch with the mayor for quite some time, she finally made that call, and we immediately took action."
Mayor Stephanie Rawlings-Blake defended the delay.
"I spent a big portion of the day working to assemble additional resources so we can bring calm to the city," Rawlings-Blake said.
After a day marked by property destruction, looting and fires, Maryland state police are now running the show in the city of 620,000, and the National Guard is taking its orders from Maj. Gen. Linda Singh.
"We are going to be out in massive force we are going to be patrolling the streets, we are going to be coming in with up-armored humvees," Singh said.
The violence began in northwest Baltimore, just hours after Freddie Gray's 11 a.m. funeral. By 4:30 p.m., dozens were attacking a police cruiser. Within two hours, droves of people were seen looting CVS, and it was set on fire. Officers in riot gear were deployed, but Baltimore Police Commissioner Anthony Batts noted that their resources were stretched thin.
"Baltimore is almost close to about 80 square miles ... We had opposite ends of the city pulling us at the same time," Batts said.
At least 15 officers were injured in what Batts called a very "trying and disappointing day."
"They just outnumbered us and outflanked us. We needed to have more resources there," Batts said.
Councilman Brandon Scott said his constituents still feel the effects of decades-old violence.
"The neighborhood they're in right now has still been burned down from 1968," Scott said.
1968 was the last time the Maryland National Guard was activated for a public disturbance in Baltimore, after the assassination of Martin Luther King Jr.
Baltimore will be under curfew starting at 10 p.m. ET Tuesday.
And what remains are unanswered questions about what happened to Freddie Gray. The mayor has promised the results of the police department's investigation by Friday.