The blaze broke out Friday night in the two-story building, which housed artist studios and events and was hosting an electronic music show. At least nine people were killed, officials said.
Officials estimated at least 100 people were at the show, which a Facebook page
called the "Golden Donna 100% Silk 2016 West Coast Tour."
That Facebook page has since become a clearing house for information where people are posting names and photos of attendees and asking where they are.
One woman wrote that her son "is missing still. as time goes on reality is slowly clawing its way into our hearts. there are no words."
Another woman wrote, "My cousin is missing, we're worried sick. Sending love to everybody affected by this tragedy."
Showgoers who made it out of the warehouse safely are also using the page to let people know they're safe.
wrote on the Facebook page: "I arrived just as the first fire trucks were pulling in. The place was already ablaze. There were huge flames coming out of the roof. And tons of billowing black smoke.
"On the sidewalk, where many of my friends who attended were huddled, you could feel the heat of the flames. Most of us were crying or unable to react. It was so hot and so terrible knowing that so many of us were still inside."
Several commenters also offered assistance. "Folks who need a place to stay? I have places. Please send me a message. We are here for you, you are not alone," one person wrote.
Distressed relatives and friends have also taken to Twitter to ask for help locating missing people, and are using the hashtag #OaklandFire
Other Twitter users, including celebrities and politicians, have offered prayers and support to the victims.
"Our thoughts are with the entire city in this difficult time & we extend our condolences to the family & friends of those lost," California Gov. Jerry Brown tweeted.
To assist in the search efforts, Facebook activated its Safety Check,
which allows users to easily notify friends that they are okay.
The city of Oakland has also offered its assistance in locating missing persons.
A message on the city's official Twitter account reads: "We're here to help. If you need information about a loved one in last night's fire, please call 510-382-3000."
Meanwhile, local organizations began raising funds to assist the victims
Gray Area Foundation for the Arts, a nonprofit organization based in neighboring San Francisco, set up a YouCaring page
to raise money for fire victims. The page had raised more than $83,000 by early Sunday.
The Golden State Warriors announced a donation of $50,000 to support families affected by the fire.
The Oakland A's baseball team set up a YouCaring fundraiser
and pledged to match donations up to $30,000 -- a goal contributors have already surpassed. The Oakland Raiders joined their effort later Saturday.