Mass Ave rocked by possible underground explosion

(WTHR photo)
Nighttime revelry was interrupted Monday night by a possible underground explosion downtown.

Fire crews were called to the 400 block of Mass Ave. around 8:45 Monday night on reports of a blown transformer.

Brandi Davis-Handy, a spokesperson for IPL, said they were investigating problems in an underground vault that contains transformers, calling it a "possible underground network event." She wouldn't say whether a fire or explosion took place until crews finished their investigations, but did confirm they received reports of "a flash and loud bang when the event occurred."

IFD crews also confirmed they had to put out a fire at that location, but did not say specifically what caused that fire.

IPL crews were on scene investigating the cause until 11 p.m.

Davis-Handy said it appeared a primary oil chamber in the vault failed. No word yet on why that chamber failed, but crews switched out a circuit to help fix the issue.