UPDATE: A massive explosion, followed by a fire and partial collapse, rocked the Silver Lake Nursing Home in Bristol Township, Pennsylvania, on Tuesday afternoon, killing at least two people and injuring several others. Authorities said the blast occurred while crews from PECO were responding to reports of a gas odor inside the building.

According to preliminary information, a gas leak may have caused the explosion, which originated in the basement and quickly ignited a large fire.
In a statement, a PECO spokesperson said, "Shortly after 2 p.m., PECO crews responded to reports of a gas odor at the Silver Lake Nursing Home at 905 Tower Road in Bristol Township, Bucks County. While crews were on site, an explosion occurred at the facility. PECO crews shut off natural gas and electric service to the facility to ensure the safety of first responders and local residents."
Bristol Fire Chief Kevin Dippolito confirmed that two people were killed in the incident and said multiple others were injured or remain unaccounted for. As of Tuesday evening, five people were still missing as search and rescue efforts continued.
ORIGINAL STORY: Multiple people are believed to be trapped inside the Silver Lake Nursing Home in Bristol, Bucks County, Pennsylvania, following an apparent gas explosion that caused a partial building collapse. The incident occurred around 2:15 p.m. Tuesday at the facility in the 900 block of Tower Road in Bristol Township.
Upper Makefield Township police have classified the situation as a mass casualty incident, though officials have not yet released details on the number or condition of any victims.
Videos circulating on social media show extensive structural damage to the nursing home, along with visible fire and heavy smoke.
Authorities are urging the public to avoid the area as a two-alarm fire response remains active and firefighters and rescue crews continue search, rescue, and containment operations.