The blaze gutted one unit and damaged up to three others at the Cabrillo Arms Apartments, behind St. Patrick's Catholic Church. The fire broke out about 2:50 p.m. in a second-story corner unit.
Watsonville Fire Capt. Rick Pettigrew, commanding the first engine on scene, said flames engulfed an exterior staircase leading to two second-story apartments. Two large windows at the front of a one-bedroom corner apartment had been blown out, and smoke and fire poured through the empty frames. Across the stairwell, the front door of the second apartment was in flames.
The three-man crew hooked up a hose and attacked the flames on the staircase and proceeded to the apartment, Pettigrew said. Within "minutes" the fire was out, he said.
In addition to four Watsonville units, engines responded from North Monterey County Fire and Aptos-La Selva.
Resident apartment manager Jorge Toriz said the woman in the corner apartment called him to say she needed help. He arrived to find the apartment filled with thick black smoke, and called 911.
"My first thought was for everyone to get out," said Toriz, who was the manager of the Wall Street Inn in 2005, when the landmark hotel went up in flames, the largest residential fire in city history.
The tenant declined to comment, but officials said the apartment was home to two adults and two children. All escaped without injury. A few dozen onlookers watched as firefighters mopped up and began an investigation into the cause.
Ana Torres said she lived in one of the other three buildings at the complex, and was driving by on her way to work when she saw that something was going on. Another resident told her there was a fire, so she dashed into her apartment and grabbed important documents. It was scary, she said, thinking the fire might spread.
"You never know," Torres said.
Firefighters also were looking into how many, if any, of the 11 units in the building could be occupied Thursday. It was unclear whether units below and behind the gutted apartment were damaged, and whether power could be restored immediately to any units in the building.
An estimate of damages to the building also was not available.
Toriz, the manager, didn't know the age of the building, but the Santa Cruz County Assessor's Office online records for the property date from 1969.
Representatives from American Red Cross Santa Cruz County were on scene, arranging vouchers for food and shelter for the displaced.
Patsy Gasca of the Red Cross said donations would be needed. She can be contacted at 831-600-4902.
Follow Sentinel reporter Donna Jones on Twitter at Twitter.com/DonnaJonesSCS