Tokyo police are investigating the deaths of two people after a sauna fire earlier this week. They say the couple were apparently trapped in a private room and may have died of carbon monoxide poisoning or hyperthermia.

Matsuda Masanari, a 36-year-old beauty salon owner and his 37-year-old wife Yoko, a nail technician, died after a fire broke out on the third floor of the sauna in the Akasaka district of Tokyo’s Minato Ward on Monday.

Firefighters found the door closed when they arrived. Doorknobs on either side of the sauna’s door had fallen off. They said the collapsed pair were found near the door, and the husband had been covering his wife.

Tokyo police say they have yet to determine the exact cause of the deaths, noting that the victims did not suffer injuries that would have been fatal.

The couple are believed to have become trapped in the room after they visited the sauna around 11 a.m. An employee called the fire department when an alarm sounded about one hour later.

The police say they believe the fire started when a towel touched heated stones. They are looking into the details, including when the fire broke out.

AloJapan.com