A massive fire broke out at a warehouse party in California Friday night, causing extensive damage and killing at least 36 people.

Here is what we know about the incident.

1.) Authorities are preparing for a "mass casualty" event: Thirty-three people have been confirmed dead, and others remain missing. According to the sheriff, authorities are preparing for up to 40 deaths. Oakland Fire Chief Teresa Deloche-Reed told The Associated Press that 50 to 100 people were inside the building when the fire broke out.

2.) The cause of fire is unknown at this time: While a cause for the fire has not been determined yet, Oakland Fire Chief Teresa Deloche-Reed said in a news conference that the way the warehouse was set up, with wood pallets used as a staircase to an upper floor, may have facilitated how quickly the fire spread throughout the building. The warehouse was divided into makeshift artist studios, according to Deloche-Reed, and potential exits were cluttered with art supplies. The Associated Press reported that, according to a federal official, a refrigerator or other appliance may be to blame for the fire.

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3.) Search is ongoing: Fire officials are attempting to secure the building before continuing their rescue and recovery mission. The roof collapsed during the fire, hampering search efforts. Heavy debris need to be moved so firefighters can complete a search of the building.

Authorities have removed nine bodies for the coroner to identify. Crews are working slowly, pulling debris and searching for more victims.

4.) Facebook Safety Check is active: People are using the Facebook Safety Check feature to post and seek information on family and friends who may have been at the party. The Alameda County Sheriff's Coroner's Bureau, at 510-382-3000, is also fielding calls from concerned family members.

5.) Building may have been unsafe before fire: According to the East Bay Express, the warehouse's property owner had received "habitability" complaints as recently as last month. The city's investigation was ongoing at the time of the fire. The Associated Press reported that prosecutors said murder charges are possible.

The Associated Press contributed to this report.