WASHINGTON (AP) — The Senate is returning to normal operations Tuesday following a shutdown due to the Navy Yard shootings.

Terrence Gainer, the Senate sergeant at arms, had restricted people from leaving or entering Senate buildings for part of the day Monday as authorities were searching for other potential shooters.

Late Monday, however, authorities said they believed the gunman operated alone. Thirteen people, including the gunman, died in the shooting at the Navy Yard, about a mile south of the Capitol.

Gainer said that while operations are returning to normal, the U.S. Capitol Police will maintain a high level of security at the Capitol complex.

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