She said those who died in the Dec. 2, 2016, fire "faced a nearly impossible labyrinth of the defendants' making" that prevented their escape.

Almena was arrested Monday in Lake County. Harris, who had described himself as "second in command" to Almena in managing the Ghost Ship, was arrested in Los Angeles.

Almena's lawyers, including noted defense attorney Tony Serra, said in a brief written statement that the charges "represent no less than a miscarriage of justice, and we are confident that this attempt to make a scapegoat out of our client will fail."

Deputy District Attorney Teresa Drenick said investigators had looked into the role of others in the events leading to the fire. She declined to say how many individuals had been investigated, and she declined to discuss whether further charges might be brought in the case. She said the office's inquiry into the blaze has ended.

In a three-page declaration filed in support of the charges against Almena and Harris, prosecutors outlined a history of what they describe as illegal and dangerous behavior.

In addition to the illegal conversion of the warehouse to a group residence, the declaration says, Almena "substantially increased the risk to those living, working or visiting the building by storing enormous amounts of flammable material inside the warehouse. Witnesses describe wood and other flammable objects being stored from floor to ceiling on the first level. Storing that amount of flammable material in the manner described by witnesses and shown in photographs, created an extremely dangerous fire load and was a violation of the Oakland Municipal code and the California Fire Safety code."

The document describes Harris' role as "creative director" of the Ghost Ship facility, responsible for collecting monthly rent from the warehouse's approximately 25 residents, acting as go-between with the building's landlord and arranging entertainment events at the venue.

The night of the fire, the declaration alleges, Harris helped prepare for an electronic music performance on the building's second floor. The main access to the area was a jury-rigged staircase made of wooden pallets.

"In the course of his preparation," the document says, "Harris blocked off an area of the second floor that included a second stairwell, which effectively reduced the upstairs guests to a single point of escape. Because of the fire, the power to the building went out and the guests that could escape, were forced down the narrow makeshift stairs in complete darkness."

O'Malley said that under California's homicide statutes, prosecutors "must be satisfied that any defendant acted with gross or reckless conduct akin to a disregard for human life, and that the deadly consequences of those actions were reasonably foreseeable."

Monday's charges and arrests come after a long series of reports that detailed dangerous living conditions in the 31st Avenue warehouse, which had been converted illegally into a residence. Those conditions -- also enumerated as allegations in lawsuits filed against Almena, the building's owners and others -- included substandard, unlicensed electrical work.

Investigators still have not made an official ruling on exactly what sparked the fire, but reports in the days after the blaze suggested that an electrical fault was likely to blame.

The fire broke out just before 11:30 p.m. on Dec. 2 during a Friday night dance party at the warehouse. About 100 people were attending the event in a space that had never been inspected by the city or granted permits for public events. Perhaps two dozen Ghost Ship residents were also at home. Almena, his partner and their two children were staying in a hotel in downtown Oakland.

The blaze sent partygoers and residents scrambling to escape.

Those who fled, and the firefighters who attempted to enter the burning structure, described encountering a maze consisting of old pianos and furniture that, combined with heavy smoke, made it difficult to get out of or into the building.

The jury-rigged stairway made of wooden pallets burned, cutting off the escape route for dozens of people on the building's second floor.

Thirty-five concertgoers and one resident died.

The tragedy exposed a series of apparent failures or lack of follow-through in Oakland's fire and building inspections.

Although the Oakland Fire Department had said it conducted yearly inspections of the city's commercial and large residential buildings, it had no records of ever inspecting the Ghost Ship building.

The building and an adjacent property -- a debris- and vehicle-filled vacant lot also owned by landlord Chor Ng -- had been the subject of repeated blight complaints. The city's Planning and Building Department received at least two reports that suggested the structure had been converted, illegally, into a residence.

In one case, a city inspector said an unpermitted structure had been removed from the building. The city says that a second complaint, received three weeks before the fire, focused on the adjacent junk-strewn lot, not the warehouse itself.

Warehouse neighbors reported calling Oakland police repeatedly about noise and other issues at the warehouse -- including the possibility people were living there illegally.

The city later released records that showed 19 separate calls to respond to the warehouse.

Among those calls was a March 2015 incident in which officers responded to a 2 a.m. call that a rave, complete with illegal alcohol sales, was occurring in the building and that 15 people inside were not being allowed to leave. One of the responding officers confirmed the situation and notified an unidentified person at the Ghost Ship that the event was in violation of city ordinances, but decided not to issue a citation.