US authorities were investigating the source of a mysterious gas-like odour that spread across a large part of Manhattan and prompted officials to evacuate buildings and temporarily suspend some commuter rail services on Monday.
The strength and wide spread of the odour brought jitters to a city that is constantly reminded of the September 11 attacks. But a US Department of Homeland Security spokesman said "there is no indication at this time of a terrorism connection."
Mayor Michael Bloomberg said the odour was not dangerous.
"It may just be an unpleasant smell, but at this point we do not know any more than that. The one thing we are confident about is, it is not dangerous," he told a news conference.
Fox News quoted NYPD too as saying the smell was not harmful.
There were no immediate reports of injuries.
The Fire Department began getting calls about the odour around 9 am, spokesman Tim Hinchey said. "The smell was very strong. It was very scary," Yolanda Van Gemd, an administrator at ASA, a business school near the Empire State Building, said. The school was evacuated as a precaution.
Across the Hudson River in Jersey City, Maria Pignataro, the spokeswoman for Mayor Jerramiah T Healy, said officials were told the odour in their city was due to a gas leak in the Chelsea section of Manhattan.
Officials from utility company Consolidated Edison had no comment.