UPDATE: Underground blast rocks downtown Indianapolis

A series of small underground transformer explosions rocked downtown Indianapolis on Wednesday, sending brownish-gray smoke billowing into the streets and forcing evacuations from nearby buildings.

The explosions about 1:30 p.m. outside the Circle Centre shopping and entertainment mall rattled windows and sent police officers rushing into the area to evacuate workers and other onlookers to a safe distance away, Indianapolis Fire Department Capt. Rita Reith said.

No one was injured.

"It was just boom, boom, boom, boom, boom, and then they cleared the entire block," Mark Neyland, an operations manager for the Indiana Housing and Community Development Authority, told The Indianapolis Star. The agency has its offices near the site of the explosions.

Bruce Plott, a construction worker who was nearby, said he heard what sounded like someone banging on aluminum garbage cans as he walked down some stairs around the corner from where the explosions occurred.

"It went on for almost 10 minutes," Plott told WIBC-FM. "It was pretty scary, so I walked around the corner and saw the smoke coming out of the sidewalk."

Mayor Greg Ballard and Public Safety Director Troy Riggs went to the scene for briefings from firefighters and Indianapolis Power & Light, Reith said.

IPL issued a statement saying a network protector failed in an underground vault holding four transformers that provide power to part of the mall. IPL cut power to two restaurants and a portion of the mall while it investigated the failure.

The evacuated workers included about 30 employees in state courts administration. Indiana Supreme Court Chief Justice Brent Dickson authorized letting them go home for the day after they collected belongings from their work space inside one of the evacuated buildings.

The blast closed busy Meridian street to traffic for more than three hours.

A series of downtown manhole explosions in 2011 brought IPL under scrutiny by state regulators.