New Hampshire hospital evacuates emergency and operating rooms after complaints of nausea

— -- A hospital in Exeter, New Hampshire, was partially evacuated Friday after mysterious complaints of nausea and lightheadedness, officials said.

The incident occurred at Exeter Hospital around 11:15 a.m. ET. Nineteen staff members were sickened in the operating room. Fire crews were dispatched, and both the operating room and emergency room areas were evacuated and closed, according to a hospital spokesperson.

The rest of the hospital was safe, the spokesperson said.

The operating room staff members were medically evaluated and 12 staffers were transported to nearby hospitals. Everyone is doing well, a spokesperson said later on Friday.

Six patients were removed from the emergency room as a precaution, the spokesperson added.

In a press conference Friday evening, a spokesperson said everything is back to normal and that there is no concern at this time at the hospital. After conducting several tests, the hospital deemed that whatever was there this morning is no long there, the spokesperson said.

While the situation was abnormal, the spokesperson said he felt comfortable giving the all-clear.

All 19 hospital staffers were discharged after they underwent thorough examinations and testing, the spokesperson said.

Investigators are working to determine the cause of the mysterious symptoms.

The next step is to thoroughly clean the building the spokesperson said, but it is unclear when the operating room and emergency room areas will reopen.

The Exeter Police Department urged residents and local fire departments via Twitter to not bring new patients to Exeter Hospital due to the evacuation.

ABC News' Gregory Croft contributed to this report.