The MBTA decided to close some of its Boston stations during massive protests Sunday because the agency's top public safety official on scene determined that "outside activity posed a danger to the safe operation of the station and transit activity," General Manager Steve Poftak said.

Trains skipped most stops in the downtown area, including Park Street, Downtown Crossing, Government Center and Haymarket, on Sunday night after earlier peaceful protests with tens of thousands of people turned into a clash between police and a smaller number of individuals.

In a lengthy Wednesday night statement, Poftak explained the steps MBTA officials take to assess service responses during marches and demonstrations, adding that the T suspends or closes stations "for safety concerns only."

Poftak said the Transit Police Incident Commander decided Sunday to take stations offline amid a "very unsettled scene and a fluid situation."

"A disorderly situation in a station poses significant risks to riders, T employees, and critical T assets such as vehicles and signal systems," Poftak said. "An accident, a deliberate act, or trespassing poses a significant risk of an incident -- including contact with the third rail, potential to be struck by a moving vehicle, injury to another rider or employee, and a risk to our employees and customers in the form of secondary trauma due to the injuries caused and/or witnessed."

Some stations were also closed to the public for shorter periods \during demonstrations Monday, Tuesday and Wednesday.

Protests against police violence have swept across the country over the past week following the alleged murder of George Floyd, an unarmed black man, by white Minneapolis police officer Derek Chauvin.