The sound of a massive explosion rocked Manhattan's Financial District Thursday afternoon, causing alarm and at least one minor injury.  

 

The boom rang out around 4:15 p.m. on Nassau Street between Liberty Street and Maiden Lane alongside the Federal Reserve building. FDNY officials said a manhole cover blew, and ConEd said they got reports of a smoking transformer and that crews were en route. A Metro reporter at the scene said responders had stretchers at the ready on Maiden Lane, but it was loaded back into the ambulance without anyone needing treatment. 

 

However, just before 5:30 p.m., FDNY tweeted that multiple buildings in the area have “high levels of CO” and one person suffered a non-life-threatening injury.

 

Startled New Yorkers ran from the area immediately after the blast. Police and fire officials taped off the surrounding streets. A security official at the Equitable Building nearby said there was no immediate threat or cause for alarm. Witnesses used Citizen App to document what unfolded after the explosion, with onlookers claiming a vehicle had been damaged.

 

Tania Santiago heard "what sounded like an explosion or a piece of metal being dropped" from her office on the 29th floor of 1 Liberty Street. She chalked it up to some of the nearby construction taking place and came down to the street, where she stood on the corner of Liberty and Nassau with a crowd of bystanders. 

A Downtown Alliance security officer who was patrolling near Cedar Street and Broadway told Metro he "thought it was thunder." 

People reported hearing the alarmingly loud noise on Twitter.

About 20 minutes after the first explosion, a second big boom was heard, and NYPD officers on the scene urged the crowd to move back. 

Metro staff reporter Nikki M. Mascali contributed to this report.