Frank Ryan, 41, is in still in critical but stable condition after undergoing surgery on Thursday, fire Capt. Mary Gutierrez said.
Ryan collapsed after suffering cardiac arrest a few minutes before noon on Thursday, just as fire crews were gaining the upper hand on a three-alarm fire at St. Patrick Proto-Cathedral Parish at 389 E. Santa Clara St.
According to Gutierrez, firefighters faced "blackout" conditions inside the church, meaning there was so much smoke that it was difficult to see.
About 40 firefighters, police officers and community members gathered for a late-afternoon prayer vigil for Ryan on Sunday in the parking lot of Regional Medical Center of San Jose, where he is being treated, according to Gutierrez.
"We have firefighters there around the clock, we want to be there in case there is any significant change," Gutierrez said.
She said that at any given time, at least 20 firefighters are standing by in the hospital's intensive care unit waiting room. A handful of off-duty firefighters have been spending the night on cots each night.
Gutierrez also said firefighters and their families have been raising money to cover travel expenses for Ryan's family, who live outside the Bay Area, including about $1,300 collected in a Styrofoam cup in the hours after Ryan was hospitalized.
So far, the donations have been used to fly Ryan's three sisters and two brothers to San Jose. Ryan is not married and does not have children, Gutierrez said.
"In the fire family, in the fire department, if you have a firefighter who is seriously injured -- on duty or off duty -- there will always be firefighters to support them," Gutierrez said.
"We'll make sure that the firefighter and the family will be taken care of," she said.