Updated 10:38 a.m. | Capitol Police sealed entrances to the Capitol Visitor Center shortly after 9 a.m. on Tuesday, in response to a suspicious substance.  

Trapped groups of tourists and tour guides milled about in the main level, waiting for an all-clear so that they could enter the Capitol as police investigated in Emancipation Hall.  

Escalators to and from the Capitol and outside entrances were ordered closed, as police implemented a shelter in place.  

Capitol Police spokesman Shennell Antrobus confirmed the investigation to CQ Roll Call.  

At about 9:50 a.m. Capitol Police radios began buzzing with the news that the suspicious substance tested negative and normal operations would soon resume, once the HAZMAT team cleared the scene.  

A group of about 30 tourists who had been led out of the CVC theatre during the 45-minute investigation geared up for their tour of the Capitol. An officer joked with them that the well-rested CVC tour guides, also waiting for an all-clear signal, would show them a great time once operations resumed.  

Shortly before 10 a.m., word spread that the doors and escalators were re-opening. A handful of Capitol employees who had been waiting in the Crypt boarded the escalator down to the CVC. Outside, emergency vehicles parked on the East Front prepared to depart. A long line of tourists waited to enter the screening facility.  

Antrobus confirmed in an email that the substance had tested negative and the CVC would re-open shortly.  

A steady stream of tourists poured into Emancipation Hall.