Sept. 9 (UPI) -- Police in Hong Kong raided the city's Tiananmen Massacre Museum on Thursday after a group that hosts vigils to honor victims of the 1989 massacre refused to hand over information.
Authorities said the raid was part of a national security investigation.
The center, also known as the June 4th museum, displays information and historical items related to the massacre.
After hosting a new exhibition in June, the museum was closed for operating without a required license. The Alliance, which runs the museum, said it would reopen and operate separately from the group.
Hong Kong authorities say the museum operators have been working as foreign agents.
Officials say museum leaders were arrested Wednesday for refusing to hand over some items in the museum. They face six months in prison and a $13,000 fine.
Police on Thursday removed boxes of items from the museum, including exhibit display panels and cardboard cutouts.
Both U.S. and British officials have spoke against the arrests, saying they're abuses of power under the guise of the Chinese territory's controversial national security law.
The raid occurred on the same day that a dozen activists from the Hong Kong Alliance in Support of Patriotic Democratic Movements of China pleaded guilty over a banned Tienanmen Square vigil last year.
A number of people died at Tiananmen Square in China on June 4, 1989, when the Chinese military used force to quell a student-led protest against controversial reforms by the government in Beijing.