Maynard, MA — Investigators have determined that a gas leak caused the explosion and fire that killed one person and injured three first responders last week in Maynard, Massachusetts.

The fire department received a call at 4:10 p.m. on Thursday about a potential gas leak at 27 Park St., and firefighters found smoke and flames when they arrived. The fire grew quickly, according to the office of State Fire Marshal Peter Ostroskey.

Firefighters entered the home and found one man, in his 60s, deceased inside.

The fire took about two hours to fully extinguish.

Two police officers and a firefighter were hospitalized with injuries that were described as non-life-threatening. They have since been released from the hospital.

According to the State Fire Marshal, the investigation into the fire included the excavation of nearby gas lines. They determined that a leak in a gas line outside the home, rather than in an appliance.

The gas spread and ignited in a basement crawlspace near the front of the building.

“As this fire demonstrated, it’s important to treat a potential gas leak as you would a fire alarm,” said State Fire Marshal Ostroskey. “Natural gas and propane are treated with a substance that has a distinctive odor that smells like rotten eggs. If you can smell it in your home, go outside to call 911 right away. Don’t smoke or use any electrical appliances, even a light switch or thermostat, because any spark could lead to an explosion.”

Eversource began testing all gas services in Maynard on Friday. The fire department said the work will continue through this week.

Additionally, Maynard Fire Chief Anthony Stowers says the department and Eversource responded to two simultaneous gas leaks on Saturday morning.