The fire started at about 3:10 p.m. in a former television station at Park Avenue and S. Montgomery Street, which is about two blocks from a Caltrain station. At its peak, the smoke could be seen as far as Great America Parkway.
Crews battled the five-alarm blaze that, at one time, had them concerned that it would spread.
The non-residential building once housed a local TV station and is across the street from a San Jose Fire Department training center.
Officials were worried about a possible structure collapse and ordered all crews to stay 100 feet away from the building. About 30 minutes after the first call was reported, officials say a wall partially collapsed.
"This is a five-alarm fire," said Captain Reggie Williams. "The fire has been mostly knocked down. We have it completely surrounded with our area ladders. We've had multiple collapses. We are interviewing some people that were inside the building at the time of the fire. We need to try to figure out whether everybody's accounted for, whether everybody got out safely. During the fire, because of the high heat, we had a couple firefighters get injured. Some suffered some minor burns, others exhaustion after fighting this fire for such a long time."
Some may be familiar with this location -- it's part of the A's ballpark plan.
The fire did not seem to disrupt Caltrain service.
Residents nearby say the building has been vacant for some time and is continually tagged with graffiti.
Captain Williams says the building had been used by squatters. When they arrived, as many as eight people were trying to retrieve possessions. Officials say one man even stored his motorcycle inside the building.
Investigators do not have a cause yet, but have confirmed that they are speaking with a few individuals who were seen at the location at the start of the fire.
Officials say two firefighters were injured and at least one fire truck sustained some damage.
Crews used multiple hoses to battle the blaze and will remain on scene to secure the building and tend to any hotspots.