Coroner IDs woman killed in irrigation tunnel collapse near Knights Ferry
A woman killed in the collapse of an irrigation tunnel near Knights Ferry has been identified as Twyla Capurro, 35, of Coulterville, authorities said Wednesday.
She was in the tunnel when it collapsed Tuesday afternoon at a work site near Schell and Sonora roads in Calaveras County near its border with Stanislaus County, according to fire officials. Another worker was outside the tunnel when firefighters arrived and was treated for minor to moderate injuries that were not considered life-threatening.
The site is part of the Canyon Tunnel Project, designed to improve reliability for the Oakdale and South San Joaquin irrigation districts. In a joint statement Wednesday, they said they are working with investigators looking at the possible cause:
“SSJID and OID extend their deepest condolences to the family, friends and loved ones of those involved in yesterday’s incident. The districts thank all the first responders across multiple jurisdictions who responded to the project site and coordinated their efforts in rescue and recovery. We further offer our thanks and condolences to construction team, as they worked in conjunction with first responders in the rescue and recovery of their own. Our hearts are with everyone touched by this tragedy.”
Firefighters were dispatched at about 3:45 p.m. Tuesday. Capurro remained trapped inside the tunnel and was later declared dead at the scene, according to the Modesto Fire Department.
Fire crews spent hours working to safely access Capurro in a hard-to-reach area about 200 feet into the tunnel, Modesto Fire Capt. Joe Spani said. The recovery effort required specialized technical teams trained in confined space and collapse incidents.
Firefighters had to take precautions to prevent additional cave-ins while working in the tunnel.
Capurro’s body was recovered from the collapsed tunnel at about 10 p.m., according to a news release from Modesto Fire. All emergency personnel cleared the scene at approximately 11 p.m.
The response involved more than 30 firefighters from multiple agencies and was managed under a unified command that included the Copperopolis Fire Protection District, Modesto Fire Department, Stanislaus Consolidated Fire Protection District and the Calaveras County Sheriff’s Office.
The Stanislaus County Sheriff’s Office also assisted with drone operations inside the tunnel, providing critical situational awareness during the recovery effort.
Chief Scott Hertzog of the Copperopolis Fire Protection District described the incident as devastating for responders.
“My heart’s broken,” Hertzog said. “It’s a very tragic situation.”
Hertzog said the complexity of the incident required resources beyond what his rural department could provide alone.
“This level of technical rescue is not something attainable in our small fire district,” he said. “We rely heavily on mutual aid from neighboring agencies.”
This story was originally published April 15, 2026 at 11:10 AM.
