The incident occurred about 2:30 a.m. as firefighters were battling the fire on the city's near east side.
A freelance photographer working for the Indianapolis Fire Department was shot in the arm.
WISH-TV photographer Kevin Hankins says he was filming the scene when he was shot in the back. He said he felt and heard a smack, lifted his shirt and saw that he was bleeding.
Police say bullet also apparently struck an air tank worn by a firefighter, but the firefighter was not injured.
Police are looking for the gunman. The cause of the fire is under investigation.