Two adjoining Fishtown rowhouses collapsed Sunday morning, sending rubble crashing and dust billowing after a contracting company had been working in one of the properties without proper permits or safety precautions.

The homes were at 633 and 635 E. Thompson St. in the heart of Philadelphia’s fast-gentrifying Fishtown neighborhood. The Department of Licenses and Inspections had declared both properties imminently dangerous on Friday afternoon. Last week, a contracting company excavated the basement of the unoccupied house at 633, destroying the shared foundation wall, said L&I spokesperson Karen Guss.

The family that owned 635 did not realize that the foundation had been compromised until Friday, when “the house shook, the ceiling started to cave in, the floors started to sink, and the stairs separated from the wall,” said Karen Klenk, whose mother, 94, owned and lived in the building.

L&I concluded Friday that both properties needed to be torn down as soon as possible, as they were too unstable without support from the weight-bearing foundation wall. Klenk’s mother, Clovena, as well as a sister and brother who also lived there, evacuated immediately.

City officials arranged for demolition to occur Sunday.

“The properties were so unstable that machine demolition" — as opposed to demolition by hand, which is how most rowhouse demolitions in Philadelphia are done — "was necessary to get the properties down promptly and to protect demo workers by keeping them at a greater distance from the properties,” Guss said in an email. “This concern was well-founded, as the properties collapsed in their entirety as the demolition began.”

L&I identified Philadelphia-based Q Construction Group as the contractor of record, but Guss said the department is investigating to determine whether other contractors were involved. Q Construction in November obtained an alteration permit for 633 E. Thompson to cover “basic renovation and repairs," Guss said.

The permit “most certainly did not authorize excavation or any kind of work on load-bearing walls,” Guss said.

A telephone number associated with Q Construction was out of service Monday.

Guss said that in addition to not having proper permits, the contractor failed to file an engineer-designed plan for protecting the adjacent property, as required by Philadelphia’s building code. In addition, no code-mandated engineer was onsite to ensure that the plan was executed properly.

“The lives of everyone working on and occupying 633 and 635 were in jeopardy, and it is a great relief that they escaped death or injury," Guss said. She added that L&I expects to take action to revoke the contractor’s license.

The property at 633 was purchased by E. Thompson Development LLC for $100,000 in 2017, property records show, in a deal that included 631 E. Thompson, next door. E. Thompson Development was incorporated that year by Walter Marino, according to state records.

Marino is also listed as the founder and CEO of 1217 Realty Group, a Mount Laurel-based real estate investment and development company that has multiple construction projects in Philadelphia. He did not respond to a request for comment.

As Philadelphia has experienced a surge in redevelopment and new construction, the city has also seen numerous building collapses. The 2013 collapse at the Salvation Army thrift store that killed seven people is remembered as among the most deadly and prominent, but many other buildings have collapsed in the years since. Last year, a building in Brewerytown collapsed on two construction workers, killing one, during a job that required demolition by hand. And in December, a property in Francisville collapsed on a crew of contractors as they worked on a project, momentarily trapping two under the rubble.

Clovena Klenk bought 635 E. Thompson, which was constructed in the early 1900s, with her husband in 1958. They raised 10 children there. Often, the Thompson Street property was the gathering spot for birthdays, parties, and holidays of the children and 17 grandchildren. Sunday dinners and football were traditions.

“It stings,” said Karen Klenk. “When the house came down on Sunday, I lost any composure I had. That could’ve been my brother, my sister, my mother, and her nurse under that rubble.”

Before the house fell, one of the elder Klenk’s sons, with supervision from officials on the scene, entered the house one last time. He emerged with his mother’s wheelchair, walker, medication, and ID before stopping to grab her late husband’s military flag. He had died in December 2017, the same month that E. Thompson Development purchased the property next door.