According to CBS News, the National September 11 Memorial & Museum was briefly evacuated on Sunday after multiple visitors called police to report chemical fumes. Authorities say the odor was caused by an excess of cleaning agents used in the memorial’s reflecting pools.

The FDNY tells Gothamist that they began receiving reports of possible fumes just after 2 p.m., finding “some kind of cleaning agent for the pool.” Witness at the scene report the chemical was chlorine.

Just before 5 p.m., Fox 5 reporter Stacey Delikat tweeted that the memorial was back open after the affected pool had been shut off.

[Image via AP Images]