Police were guarding the scene of a suspicious early morning fire in Dundas on Sunday.

Police say they were called to an abandoned, dilapidated building that was burning on Old Ancaster Road near Osler Drive around 5 a.m.

The house was fully engulfed in flames when fire crews arrived, said fire official Claudio Mostacci. The incident is being treated as suspicious as "vacant buildings don't usually catch fire," he said.

Officers were holding the scene until the Ontario Fire Marshal's office arrived. No one was inside at the time, and no one was injured, police say.