Police say a transformer explosion has caused an underground fire and power outage in a section of New Jersey's largest city.

Newark police say Public Service Electric & Gas was working on the transformer when it caught fire and exploded around 11:30 a.m. Friday.

Workers in the IDT building say they heard a loud boom and everyone evacuated the building.

EMS says two workers were injured. Their conditions are not yet known.

Black plumes of smoke are coming from the ground as firefighters try to extinguish debris that ignited.

Many buildings in downtown Newark are without electricity. Police have closed Broad Street between Bridge Street and Central Avenue.

PSE&G says it's trying to determine extent of damage.