Two people who were found dead after a fire at a sauna facility in the Akasaka district of Tokyo¡¯s Minato Ward on Monday may have been trapped as a result of a broken door, investigative sources said Tuesday.

The L-shaped handles of the sauna unit¡¯s door were found on the floor inside and outside the unit, according to the sources.

The sources also said Wednesday that on-site investigations conducted on Tuesday found the fire alarm control panel at the facility¡¯s operation office had been turned off, suggesting the possibility that alarm buttons at all of the sauna units had not been working at the time of the incident.

The plastic cover of an emergency button of the sauna unit where the fire broke out was broken. Investigators believe the victims might have tried to push the button after noticing something abnormal.

The two victims ¡ª Masaya Matsuda, a 36-year-old beauty salon owner, and his 37-year-old wife, Yoko, a nail technician ¡ª were found collapsed near the door inside the sauna unit.

The Metropolitan Police Department is investigating whether the victims were unable to escape because the door was inoperable, as well as how the facility, called SaunaTiger, was managed.

In the sauna unit the victims used, parts of the wooden bench, including the backrest and seat, were charred, and a burned towel was left on top of the bench, according to the sources.

On Monday, a fire alarm outside the sauna unit sounded at around noon, prompting an employee to make an emergency call. The victims had booked the private room with the sauna unit from 11 a.m. to 1 p.m.

The police plan to perform autopsies as early as Wednesday to determine the exact cause of death, and will look into whether there were any shortcomings in the safety measures of the sauna operator, Sauna & Co.

The company said on its website that it takes the incident seriously and deeply regrets the loss of precious lives, adding that it will work closely with relevant authorities to determine the cause and prevent a recurrence.