A man was arrested Wednesday outside the Agriculture Department after claiming to have explosives in a van and making threats against President Bush, police said.

The 38-year-old man from Woodbridge, Va., was taken to George Washington University Hospital here and held for observation, District of Columbia police spokesman Joe Gentile said. Police did not release the man's name, pending an investigation.

A police bomb squad fired a water cannon at two suspicious packages found in a rental van the man had parked outside the department. Neither was found to contain explosives, police spokesman Quintin Peterson said.

An officer with the Federal Protective Services was first alerted to the man. The FBI and D.C. police were questioning him, and the Secret Service was looking into whether to charge him with threatening the president, Peterson said.

Morning rush-hour traffic was brought to a standstill as several streets were closed in the area, and about 7,000 people were evacuated.

Officials tore open a file box full of books from the van and inspected a suitcase and clothing bags, and the FBI confiscated the truck.

People were allowed back into the building and the roads reopened by midmorning.