The three-alarm blaze in Willimantic that sent nine people to the hospital early Tuesday morning was set, according to officials in Windham.
A $2,500 reward is being offered for information leading to the arrest and conviction of whoever set fire to 62-64 South Street.
The fire broke out just before 1 a.m., and one man, Dave Marshall, jumped from a third floor window of the six-family house at 62-64 South Street, tumbled down 20 feet and broke his hand in the fall, but he was able to alert firefighters that his wife, Kathy Hill, was still trapped inside.
Captain Ron Plamer and firefighter Chad Molochnick rushed into the apartment and rescued the woman, who was in full cardiac arrest, officials said.
Emergency crews performed CPR and the Lifestar helicopter took the Hill to a Rhode Island hospital.She remains in critical condition on Wednesday. Her family is flying in from New Zealand to be by her side.
Hill, a researcher at UConn, was reported to be breathing on her own when she was transported. Her condition is not known because of patient privacy laws.
Three residents, including Hill, and six firefighters were taken to the hospital. A man who lived on the first floor had chest pains, but is OK.
Four of the six units were being rented, officials said and one resident was out of town when the fire started.
Officials said the house will likely have to be torn down.
Marshall is also a researcher at UConn, according to Hill's online bio. On Wednesday, Hill's colleagues from UConn gathered across the street from the couple's house.
Local officials are turning the investigation over to the state police major crimes unit.
If you have information that will help investigators, call the Connecticut arson hot line at 1-800-842-7766 or Lt. Paul Vance, at Connecticut State Police.