UPDATE: Underground Blasts Rock Downtown Indianapolis

INDIANAPOLIS (AP) _ The Indianapolis Fire Department says a series of small underground transformer explosions has rocked downtown Indianapolis and forced evacuations. 
Capt. Rita Reith  says the explosions Wednesday afternoon about two blocks south of Monument Circle shook windows and shut down traffic in both directions for at least two hours.
Reith says police quickly moved evacuated workers and onlookers to a safe distance away. She says Mayor Greg Ballard and Public Safety Director Troy Riggs went to the scene for briefings from firefighters and Indianapolis Power & Light.
Reith says the cause of the explosions is under investigation.
Several 2011 downtown manhole explosions brought IPL under scrutiny by state regulators. Reith says Wednesday's explosions did not displace any manhole covers.
A message seeking comment was left for an IPL spokeswoman.