An investigation into the Hopkins house explosion that killed an elderly couple in July has been completed.
Hopkins Police, along with the Minnesota State Fire Marshal, said an unattached gas line is to blame for the explosion.
The incident killed Herb, 85, and Sharon Vassar, 83.
According to police, the investigation revealed that the house's water heater was recently replaced, with a gas line not getting reattached following the installation. The home is in the area of 2nd St. N. and 21st Ave. N.
"This allowed gas to leak into the residence and eventually ignite," authorities said. Investigators aren't sure what caused the explosion, noting that natural gas can be ignited by anything from "light switches, static electricity or pilot lights," among other sources.
The explosion and fire has been ruled an accident.