Just before 9 p.m., fire crews were dispatched 16th and Broadway streets on reports of a structure fire.

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An earlier tweet sent out by the Department of Public Safety that indicated an electrical cause was actually in reference to another apartment blaze, fire officials said late Saturday morning. The cause of this fire is undetermined.

Heavy smoke and flames could be seen from miles away, billowing from third-phase construction of 16 Park, an apartment building, RTV6's Tanya Spencer reported.

"The first arriving crews were faced with heat so intense it scorched paint on some fire apparatus," said Indianapolis fire Lt. Larry Tracy.

Fire officials said the blaze took over an entire city block.

"We didn't know what was going on. We were worried that it could have been a disaster, maybe a plane crash," resident Ryan Daly said.

"I've never seen anything like it," witness Ruth Harris said.

Crews worked to prevent the fire from spreading to nearby buildings and a church.

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RTV6 received many calls from viewers who said smoke could be seen for several miles, spanning from Indianapolis' south side into Hamilton County to the north.

Officials said several firefighters were overcome by the heat. They were treated on scene and were not seriously injured. Another firefighter suffered a broken wrist.

The four-story apartment building would have housed 28 units and was slated to open this fall, the Indianapolis Housing Agency said. Two occupied buildings in the same complex were not seriously damaged in the blaze.

"Thankfully, no current IHA residents were seriously injured," the agency said in a news release. "IHA wants to thank the men and women of the Indianapolis Fire Department and the Indianapolis Metropolitan Police Department. Their work to control the scene and stop the fire from spreading was nothing short of remarkable."

IFD estimated damage to the building at $3.5 million. The cause of the fire was not determined.

Editor's Note: An earlier version of this story indicated that the Department of Public Safety determined that the cause of the fire was electrical. The Indianapolis Fire Department later clarified that was in reference to another apartment fire on Friday.