John Paul Marcelo looked up at a sniper rifle trained on his canvas.

It was around 1999, in Chicago’s Near North Side, and Marcelo was standing in front of a brick apartment building, one of the many in Cabrini-Green, a public housing project made infamous as a poster child for government neglect, poverty and rampant gang violence.

A group of more than a dozen men surrounded him, sporting firearms, watching. But rather than staring stone-faced, they were smiling — perplexed, interested.

“Hey, my cousin is watching you painting. He thinks it’s awesome,” one of the men said to Marcelo as his gaze traveled up the stairwell to the rooftop where he spotted the sniper. “I didn’t feel endangered; I was more focused on the painting.”

It was amid this backdrop that Marcelo — who now lives in San Francisco and has a studio in Oakland — got his start as a plein air, or outdoors, painter. In part, his choice of subject matter was a product of his surroundings: He was born and raised in the Chicago area, he said, and painted what was available to him.

But, even early on, his eye naturally gravitated toward documenting history unfolding, however painful. And though the walls of his Oakland gallery sport plenty of serene seaside bluffs or bridges peaking out from beneath a blanket of fog, they also include protests erupting into bloody brawls, people living in tents under freeways or the skeletal remains of a car that caught on fire.

“This is our period in time,” he said. “This is what is happening.”

It’s with this objective approach that Marcelo relates more to photographers, and especially photojournalists, than he does to other impressionist painters. But that doesn’t mean he would describe himself as a journalist, he said. He is an observer, a documentarian, capturing life as it happens.

The reality of this approach means he may have only 20 or 30 minutes to capture a scene. Sometimes, he happens upon them, he said, like when he was in downtown Oakland on Saturday night and heard gunshots ring out. Carrying a backpack filled with paint and brushes, an easel he attaches to his bicycle and several “emergency canvasses” of varying sizes, Marcelo headed to the scene, painting a cop car and ribbon of crime scene tape, he said.

In other cases, when the San Bruno pipeline exploded, for example, or when the Tubbs Fire carved a valley of ash into Santa Rosa’s Coffey Park, he may return over several days or weeks to paint the wreckage.

For Marcelo, it’s more about the process than the product. He’s less concerned about a perfect painting as he is with recording a fleeting moment before it fades, of being able to interact with people whose lives intersect the scenes he paints, of watching the light as it changes colors or smelling the air around him as he works.

But his take-it-as-it-comes mentality doesn’t mean Marcelo is agnostic to the politics that turned Cabrini-Green into a magnet for violent crime or that resulted in more and more people piling under Oakland’s overpasses. He is very much aware of the larger context within which he makes art.

He oscillates between urban and rural surroundings in part, he said, out of fear the unbridled natural world may one day succumb to human consumption and disappear, or be forever altered. He approaches California’s rugged coastline, Alaska’s glaciers and sun-soaked mountains, a grove of cypress trees, and more, as vistas that should be preserved for future generations, he said, much in the same way Ansel Adams painstakingly photographed the American West.

The landscapes he sells to make a living, he said. But he’s not yet sure what to do with the hundreds of documentary paintings he’s accumulated over the years. He rarely sells them, only occasionally permitting someone who approaches him with an idea to use them to further some social good.

For the most part, he said, they’re stacked in boxes: a treasure trove of archival footage waiting to be rediscovered and put to use.