OKLAHOMA CITY - Authorities are investigating  two structure fires that appear to be suspicious, Thursday. 

Fire crews responded to the first house fire near SW 44th & May near midnight. Crews said once flames from the back of the home were extinguished, flames from an adjacent house were discovered. Fire investigators believe the fires are suspicious and that they were each started individually.

Both homes were empty at the time of fire. 

The fires caused an estimated $35,000 in damages.

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