On June 1, SWAT teams turned a protest march in Philadelphia into chaos. We went to the site, interviewed witnesses and analyzed dozens of videos to reconstruct what happened.

Officials in Philadelphia later announced a moratorium on the use of tear gas in the city and apologized for their response to these protest against police brutality.

The announcement, by the mayor and the police commissioner, came hours after The New York Times published a visual investigation into the use of force by the police. During a confrontation with several hundred demonstrators who had entered Interstate 676 in the city center this month, SWAT officers used tear gas and pepper spray on a group of nonviolent protesters, some of whom were trapped as they tried to leave.

“I humbly apologize to those who were directly impacted as well as to our communities at large,” said Danielle Outlaw, the Philadelphia police commissioner. “As recently as today, I have viewed video posted by The New York Times by which I am extremely disturbed and, quite frankly, sickened beyond description.”