An anticapitalist group taking part in what it called the “Summer of Rage” has claimed responsibility for unrest that erupted near the University of Pennsylvania campus Tuesday night, leaving windows smashed and prompting campus police to warn students and staff to remain indoors.

Roughly 60 people in black clothes and donning black masks gathered at Clark Park, near the intersection of 43rd Street and Baltimore Avenue, and began marching just before 9:30 p.m., campus police said. They quickly cut a swath of damage along 40th Street — building barricades, vandalizing several buildings and a marked Penn police car — before dispersing about 40 minutes later.

In their wake, several businesses were left damaged along 40th Street, including a PNC bank, a coffee shop, a pizza parlor, a bar, the Free Library branch at 40th and Walnut Streets, and a university residence hall that was spray-painted with the phrase “Nerds Call 911.”

A post that appeared Wednesday morning on Philly Anti-Capitalist, a clearinghouse for local antiauthoritarian and anarchist groups, and submitted by a person claiming to be an organizer of the demonstration, declared the event a success.

“Over 45 people marched through the streets chanting and smashing windows of banks, business and developments,” the post read. “There was a surprising amount of destruction.”

It went on to describe demonstrators using barricades to elude police intervention and covering identifying tattoos and facial features to avoid detection by authorities.

Philadelphia police declined to comment on whether their investigation of the vandalism was focused on the “Summer of Rage” group, saying only that the probe continues. Penn police didn’t respond to requests for details.

But as business owners and university staff boarded up windows, cleared broken glass from sidewalks, and power-washed antipolice and anarchist graffiti off building walls Wednesday morning, many were still trying to figure out exactly what had happened. Most of the businesses along the corridor were closed when the destruction began.

Security footage at Allegro Pizza & Grill near 40th and Spruce Streets showed a crowd of people walking north on 40th just before 9:30 p.m., flanked by people walking their bicycles and halting traffic. People in the front carried a banner that read: “F— the police.”

Louie K., a part owner of Allegro who asked that his last name be withheld over safety concerns, said members of the group spray-painted on the wall of his business and a man took a baseball bat to its ATM, causing more than $10,000 in damage.

Another local business owner, who asked to remain anonymous because he didn’t “want [his] windows broken, too,” said he saw a crowd of about 25 people in black clothing ransacking a construction site near 40th and Sansom Streets.

The group threw traffic cones and toppled trash cans, he said while noting he didn’t see any violent behavior. At one point, he said, police approached the crowd near Chestnut Street and the group shouted profanities at officers but kept on walking.

The gathering that led to the unrest came together quickly through mostly private messages and social media posts. A graphic shared on Instagram directed attendees — “in solidarity with Kenosha” — to meet at Clark Park at 9 p.m. and wear black. “Screenshot & share on IG story only,” the graphic read. (Instagram’s “stories” function is not easily searchable.)

The post early Wednesday morning on the anticapitalist blog said the group was marching in solidarity with Philadelphia sanitation workers, Black Lives Matter, and protests in Kenosha, Wis., over the police shooting of Jacob Blake, the 29-year-old man seriously injured by officers Sunday as he leaned into his car in front of his children.

Organizers involved in previous protests on behalf of those causes have disavowed property destruction in their pursuit of social justice goals.

But a group donning similar dark clothing and masks and also claiming to be associated with the “Summer of Rage” drew attention in 2017 after causing more than $100,000 in damage to new buildings and high-end cars in North Philadelphia.

Those demonstrators said they were marching against gentrification in the neighborhood.

Neighbors at the time described the masked demonstrators smashing windows, spray-painting messages like “Leave!” on new buildings, and throwing Christmas ornaments filled with paint. Two protesters were arrested after area residents surrounded the group and kept them penned in until police arrived.

No arrests have been reported in connection with Tuesday’s unrest.