A firefighter was hurt Tuesday morning while battling a fire at an abandoned duplex on Kirkland Avenue in the Renton Highlands. Smoke was pouring from one of the units in the duplex when firefighters arrived. Renton Regional Fire Authority officials said there had been reports that homeless people had been living there. No one was found inside. Fire officials said a firefighter fell off a ladder and was taken to Harborview Medical Center with a hurt ankle. The cause of the fire is under investigation.