A Monday fire that critically injured a Topeka man is thought to have been caused by a natural gas leak.

According to Fire Marshal Mike Martin, the fire was at 235 NW Knox Monday afternoon just before 5:30 p.m.

Seventy-seven-year-old Vernon L. Fisher was taken to a local hospital. He was located outside the residence with injuries from the fire.

Estimated loss from the blaze is $36,000.

Working smoke detectors were not located within the structure of origin.

If you know more about this fire, call Crime Stoppers at 234-0007.