FARMINGTON — State fire investigators plan to continue their investigation of Monday’s explosion into next week, according to Stephen McCausland, spokesman for the Maine Department of Public Safety.

A fire captain was killed in the blast at the LEAP office building on Route 2 and seven others were injured, including six firefighters and the maintenance supervisor. Three remained in critical condition Friday.

Investigators from the Office of the Maine State Fire Marshal finished their on-scene work at the site Thursday night and turned the property over to its owners and their insurance company, McCausland wrote.

Fire investigators will continue their work off-site next week to try to determine the cause of the explosion. They will conduct additional interviews and analyze items gathered from the scene, according to McCausland.

Firefighters from the Farmington Fire/Rescue Department responded to a report of propane odor Monday morning at LEAP’s central office at 313 Farmington Falls Road/Route 2. Prior to their arrival, maintenance supervisor Larry Lord, 60, of Jay had gotten employees out of the building.

Lord remained in critical condition Friday at Massachusetts General Hospital in Boston. He reportedly suffered burns over 50% of his body. A GoFundMe account set up for him had reached nearly $100,000 as of Friday.

Firefighters were in the building when it blew up. Capt. Michael Bell, 68, was killed. His brother, Chief Terry Bell, 62, and Capt. Scott Baxter, 37, remained in critical condition Friday at Maine Medical Center in Portland. Their families say they are improving daily.

The condition of firefighter Theodore “Ted” Baxter, 64, the father of Scott Baxter, was upgraded from serious to fair Friday at Maine Med, according to hospital representative Caroline Cornish.

Firefighter Joseph Hastings, 24, and Capt. Timothy “TD” Hardy, 40, were released from Maine Med earlier this week. Deputy Chief Clyde Ross was treated at a local hospital and released Monday.

Thirty people were dislocated when 11 mobile homes behind the LEAP building were destroyed or heavily damaged. Vehicles were also destroyed and nearby houses were damaged.

Schoolchildren, firefighters and others across the state wore red Friday in support of firefighters, first responders and those affected by the tragedy.

LEAP is a nonprofit that works with people with developmental and cognitive disabilities.