A shed fire at a south Cambridge townhouse complex may be suspicious.

Waterloo Regional Police are investigating the fire, which broke out shortly after 5 p.m. Tuesday at 135 Chalmers Street.

The building was fully engulfed in flame by the time firefighters arrived, and suffered significant damage in the fire.

The shed was used by residents of the townhouse complex, but it’s not known what was stored inside.

No injuries were reported.