INDIANAPOLIS - A firefighter was injured early Friday battling a massive blaze that broke out at an apartment building on the city's near north side.

Just after 6 a.m., Indianapolis Fire Department crews were called to 22nd Street and College Avenue on reports of a structure fire.

"I was laying in bed and I smelled smoke," said nearby resident Michael Carpenter. "I thought the house was on fire.  I went outside and there was smoke everywhere."

Heavy smoke and fire could be seen shooting through the roof of the two-story apartment building, and crews called for additional ladder units to help douse the flames.

"(It was) just kind of a stubborn fire," said IFD Capt. Rita Burris. "It's (was) a tough morning for the firefighters."  

Burris said it took almost three hours for crews to get the blaze under control.

"In our world, that's a pretty lengthy time to be on a fire," she said.

The fight was complicated by the fact that the building was built in the early 1900s and has undergone several renovations. There were four layers of roofing to get through and lots of pockets where flames could hide.

"A lot of it has pancaked on the inside, meaning it's collapsed on the inside," Burris said. "So it's just a long and tedious process for them (firefighters) to get to the hidden spaces where the fire is located."

"You could see (the fire) drifting from the north. I saw that the building was engulfed in flames," neighborhood resident Aaron Finney said.  

At least one firefighter was taken to the hospital with non-life-threatening injuries, dispatchers said.  

College Avenue was blocked from 22nd Street through 33rd Street for at least four hours, officials said. 

Crews said the building appeared to be vacant.

"People that live in the neighborhood seem to think that (the building)  has been vacant and boarded up for some time but until we confirm, we have to do a secondary search," said IFD Lt. Derrick Sayles.

The cause of the fire remained under investigation.