New York (CNN) -- The U.N. Security Council's quarters and the General Assembly were evacuated Tuesday after officials noticed a "suspicious odor."

Diplomats were moved to a separate building within the U.N. complex, located next to the East River in Manhattan.

The incident may have been caused by high river tides, creating problems with sewage in the area and within the U.N. facility, said U.N. deputy spokesman Farhan Haq.

"It was very strong smelling and smelled a lot like gasoline," said CNN producer Whitney Hurst.

Authorities had been investigating the possibility of a combination of sulfur and methane, U.S. Ambassador Susan Rice said after speaking with fire officials.

U.N. officials later said the gases involved were not harmful, the spokesman said.

The incident delayed meetings, including a children's event in which dozens of high-school students were also relocated from the facility.

"What a way to start the day," Rice said.