MANHATTAN (PIX11) — Police cleared guests out of a Manhattan hotel floor on Tuesday after a suspicious powder was found in a vacant room, officials said.

The powder was found after a hotel employee became ill and went to the hospital, NYPD Assistant Chief James McCarthy, commanding officer of Manhattan Patrol Borough South, said. She started feeling nauseous and dizzy around 1:20 p.m. at the hotel, located 58th Street and Seventh Avenue. The woman said she’d cleaned up a white, powdery substance in a room on the 11th floor and felt sick shortly afterward.

The hotel has since been cleared and guests have been allowed back into the hotel. Operation of the hotel is back to normal, but police on Tuesday night continued looking for a suspect in connection to the powder.

“There’s no credible threat against the city at this time,” McCarthy said. “It was out of an abundance of caution that we cleared the floor of the hotel while investigating the scene.”

After the woman reported the powder, the FDNY went to the room to check it out. Since it had been cleaned and the powder was no longer visible in the bathroom, the FDNY swabbed surfaces, police said. Tests showed a possible trace of an explosive substance.

The NYPD then cleared the 11th floor of the hotel, officials said. Investigators tested more surfaces, but got negative tests with no traces of hazardous substances found. As of Tuesday night, police feel the initial test was a false positive. Investigators still don’t know what sickened the woman.

Officers are looking for a man in connection to the investigation, McCarthy said. He entered the hotel and gained unauthorized access to the room. The man was identified via a video canvas. He has not yet been located by police. The man has 16 prior arrests, all for low-level crimes.

The room he got access to was vacant, police said. The family staying there checked out on Sunday. They had five room keys and it’s believed someone dropped one and the man picked it up.

“It should have been deactivated after the family checked out,” McCarthy said. “So they’re still working on why it wasn’t.”