Capitol Suicide Bombing Attempt Halted: FBI Arrests Moroccan Man After Investigation (UPDATE)

WASHINGTON -- Fox News is reporting that authorities have arrested a man who intended to commit a suicide attack at the U.S. Capitol:

The man, in his 30s and of Moroccan descent, was nabbed following a lengthy investigation by the FBI, initiated after he expressed interest in conducting an attack. It's unclear how the FBI learned of his aspirations.

The man thought undercover FBI agents assisting him in his plot were associates of Al Qaeda.

When he was arrested Friday in Washington, he was carrying with him a vest supposedly packed with explosives, but the material inside was not actually dangerous, Fox News was told.

AP later confirmed the report.

U.S. Capitol Police spokesperson Sergeant Kimberly Schneider issued a statement on Friday stating that the arrest came after a "lengthy and extensive operation" involving the Capitol Police and the FBI:

The U.S. Capitol Police was intimately involved in the investigation for the duration of the operation. At no time was the public or Congressional community in any danger.

UPDATE: 2:45 p.m. -- Justice Department spokesman Dean Boyd has confirmed the terrorism-related arrest in Washington. "The arrest was the culmination of an undercover operation during which the suspect was closely monitored by law enforcement," he said in an email. "Explosives the suspect allegedly sought to use in connection with the plot had been rendered inoperable by law enforcement and posed no threat to the public. Additional information will be forthcoming at the appropriate time."

This is a developing story that will be updated as more information becomes available.