Thursday, December 11, 2008 – Updated 4h ago

A manhole explosion sent a power surge into Boston Police Department Headquarters, plunging cops and emergency crews into a communications blackout and momentarily eliminating the city’s 911 service, police said.

Cops and EMTs were forced to use their personal cell phones as emergency radios to respond to calls, meanwhile the screens of the mobile computers used inside police cruisers also went dark, meaning police could not run license plate information or background and warrant checks on suspects, potentially allowing wanted criminals to walk free if stopped.

“It is a huge public safety threat,” one police officer said during the outage.

A police source said a battery backup that is supposed to seemlessly transition radio and 911 service in the event of power loss had been taken off line recently after it caused a hazardous-materials scare at headquarters when the batteries began leaking.

Driscoll confirmed the battery leak but said it was too soon to say what role it played last night.

“It was dealt with at the time,” she said. “I don’t know if it had anything to do with what happened tonight.”

The city’s enhanced 911 service had shut down at least three times in the past, while technicians were installing it. Driscoll said last night’s glitch is not related to that problem.