Evidence gathered at the scene of Sunday's explosion at a Sarnia apartment building is being analyzed.
Cst. John Sottosanti said members of the Ontario Fire Marshal's Office and the Criminal Investigation Division executed a search warrant at the first floor apartment Tuesday, and the investigation is ongoing.
"At this time we are trying to determine the actual cause of the explosion, which would ultimately direct us in regards to if it was an act that was truly an accident, or if there is some sort of negligence or liability involved," said Sottosanti.
Sarnia Fire and Rescue said there were five people in the apartment at the time of the explosion, four of whom were treated on scene by Lambton EMS. A 47-year-old Sarnia man remains in a London hospital.
Over 300 tenants were forced from their apartments because of the blast, and were able to return home Monday evening.
Cst. Sottosanti said the unit directly above the first floor apartment where the explosion happened is still unoccupied, while the integrity of the ceiling in the damaged unit is examined.