Investigators say a propane leak caused the accidental Granville blast, which also injured three adults, one critically.
GRANVILLE, Vt. — A mother and her 20-year-old son were killed and three other adults were injured when a home exploded during a family birthday gathering in rural Vermont, authorities said. State investigators determined that a propane leak inside the house caused the accidental blast.
The explosion was reported at about 7:45 p.m. Sept. 5 at a residence on Connecticut Trail, off Post Office Hill Road in the Addison County town of Granville. Vermont State Police identified those killed as Liam O’Sullivan, 20, and his mother, Sarah O’Sullivan, 46, both of Essex Junction. Local news reports said family members and friends were gathered for a birthday celebration when the house exploded.
Liam O’Sullivan was pronounced dead at the scene, according to state police. First responders transported Sarah O’Sullivan to Gifford Medical Center in Randolph, where she was pronounced dead. Autopsies were completed the following day at the Chief Medical Examiner’s Office in Burlington. Authorities said both died from injuries caused by the blast.
Three other adults were taken to hospitals after the explosion. Two suffered minor injuries. Police identified the most seriously injured survivor as Shiela Hammond, 69, of Granville. The most recent public update from Vermont State Police said Hammond remained hospitalized in critical condition and was receiving treatment outside Vermont. Authorities did not publicly identify the two people who suffered minor injuries.
The Vermont Department of Public Safety Fire and Explosion Investigation Unit determined that a propane leak inside the home caused the explosion and classified the incident as accidental. Police said their preliminary investigation found no indication that the blast was suspicious. The agency did not release additional details explaining precisely how the propane escaped or what ignited it.
WCAX reported that the explosion happened while one of the two people who died was celebrating a birthday. The station also spoke with Brenda Buker, who lives down the hill from the property. Buker said she and her husband were having dinner with friends when they heard the blast and felt their house shake. Items fell from walls inside their home, she said.
Buker said fireworks had been heard from the direction of the property earlier in the evening, leading those at her home to initially wonder whether the boom was connected to them. They learned the following morning that a house had exploded. Other nearby residents reported property damage, including a shattered window, according to WCAX. Buker said her own property was not damaged.
The emergency response involved several state and local agencies. Vermont State Police personnel from the Fire and Explosion Investigation Unit, Bureau of Criminal Investigations, Field Force Division and Victim Services Unit responded. The Vermont Division of Fire Safety and the Granville Volunteer Fire Department also assisted at the scene. Investigators remained at the property after the explosion to determine its cause.
Sarah O’Sullivan had worked at the University of Vermont for 13 years, the university’s Grossman School of Business said in a remembrance published after her death. Her work at UVM included positions with Risk Management & Safety, the Rubenstein School of Environment and Natural Resources and the UVM Foundation. She spent much of her university career at the Grossman School, including service as executive assistant to former Dean Sanjay Sharma.
The Grossman School described O’Sullivan as a dedicated colleague who balanced her university work with her role as a mother and her own academic studies. The school said her death and the death of her son had affected colleagues across the university. Service plans were still being arranged when the university published its remembrance.
The blast occurred in Granville, a small community where homes can be separated by substantial distances. Buker told WCAX that the area rarely draws major news attention, underscoring how unusual the explosion was for residents. The force of the blast was strong enough to be felt at nearby properties even though some neighbors could not directly see the house from their homes.
Vermont State Police have classified the explosion as accidental and attributed it to the propane leak. Their most recent public update said Hammond remained in critical condition receiving care outside the state and that no further details were available. No later public police update changing those findings had been released as of Friday.
Author note: Last updated September 11, 2026.