A man crashed his vehicle into a security barricade at the U.S. Capitol on Monday, ran into the building and was arrested, forcing the complex to briefly be locked down, authorities said.

Police shut down the complex as they investigated the incident, and to ensure that all people there were authorized to be there. The incident happened shortly before 8 a.m., EDT, witnesses said. The Capitol complex was reopened within the hour.

Hill staffers were briefly instructed to remain in their offices while police searched to ensure there were no other interlopers.

Construction workers and police said the man had driven through a barricade at the Capitol, where a major visitors' center is under construction. His vehicle also crashed into a water fountain on the plaza in the middle of the construction area.

Witnesses said the man, wearing a blue ballcap, ran into the Capitol and was pursued by police. A construction supervisor said the man was apprehended in a construction area on the third floor of the building.

In the summer of 1998, two Capitol Police officers were shot to death when a man with a history of mental illness opened fire in the building. The man was wounded and captured.