(AP) Officials on Wednesday weretrying to determine what caused employees at Princeton Borough Hallto report feeling ill after opening a letter sent to the mayor by a70-year-old man in a Louisiana nursing home.

"There was a letter addressed to the mayor of Princeton and acouple of people who touched it, including her secretary who openedit, displayed blisters and rash-like symptoms on their face andsome people complained of nasal passages being blocked," saidMercer County Sheriff Kevin C. Larkin.

The people who came in contact with the letter receivedprecautionary treatment at the scene, according to PrincetonBorough Police Department Chief Anthony V. Federico, and theyrefused to be taken to a hospital.

Federico said some people began experiencing minor lip burningafter the first reaction took place, but that officials haven'tbeen able to determine what caused the effects.

"We don't believe it's serious," he said. "If anything, itwas an irritant."

There were about 30 employees in the building at the time of theincident, but no one had to be decontaminated, officials said.

Larkin said authorities were continuing to investigate the case,but had already spoken to the man who sent the letter, which hadanother letter inside and was addressed to the mayor, but not byname.

Larkin said the man had suffered some kind of brain trauma andbelieved he could get help from a research center in the area.

"He's a 70-year-old guy confined to a wheelchair who spends alot of time on the Internet," Larkin said.

Larkin did not know if any charges would be brought against him.

The letter was tested onsite and nothing radiological ofchemical was found, Larkin said. The letter was going to the statehealth lab for further tests.