The Secret Service said it sent out agents to investigate a possible threat early this morning, along with officers of the Metropolitan Police Department.
"The Secret Service received information from a concerned citizen and Trump International Hotel Security staff," the statement said.
"An individual was subsequently located at the Trump International Hotel in Washington, DC. Agents and officers recovered a semi-automatic assault style rifle and a handgun in the individual's vehicle."
"At no time were any Secret Service protectees at risk," the statement said, adding that the investigation was ongoing.
The Secret Service is authorized to protect the US president and vice president and their families, as well as former US heads of state and their relatives, visiting dignitaries and any other individual designated by the president.