Police in New York said Monday that a letter containing ¡°an unidentified substance¡± was mailed to the home of Donald Trump Jr.,?the president¡¯s oldest son.

Trump¡¯s wife, Vanessa, opened the letter and was taken to a hospital as a result, according to the New York Police Department.

She was ¡°not feeling well¡± after opening the letter, police said.?The Associated Press reported that she was coughing and feeling nauseated.

A preliminary assessment showed that the substance is not suspicious, said Lt. John Grimpel, a New York police spokesman.

In a Twitter message posted late Monday afternoon, Trump Jr. said that his wife and children were ¡°safe and unharmed.¡± He also suggested that the letter may have been motivated by political rancor, writing that it was ¡°disgusting that certain individuals choose to express their opposing views with such disturbing behavior.¡±

The Secret Service, which is tasked with protecting the immediate families of presidents, confirmed only that it was investigating a suspicious item sent to someone it is protecting. The agency did not specifically mention Trump Jr. or his family.

¡°The Secret Service and our law enforcement partners in New York City are investigating a suspicious package addressed to one of our protectees received today in New York, New York,¡± the agency said in a statement. ¡°This is an active investigation and we cannot comment any further.¡±

Trump Jr., along with his brother, Eric, took over managing the Trump Organization after their father won the presidency. The company did not respond to a request for comment Monday.

This story, first posted at 1:59 p.m., has been updated.