The developers seeking to revitalize the blighted area around Amtrak’s North Philadelphia station into a new complex of homes, research labs, and offices have been issued a zoning permit to build a residential mid-rise, the first solid sign of progress in the so-called North Station District plan since the land acquisition.

North Station District LLC, as the consortium of real estate investors is known, was granted permission last Friday to build a seven-story building with 135 dwelling units and ground-floor commercial space, according to Department of Licenses and Inspections records.

Michael Bailkin, a principal with consortium member Arete Group, said improved station security, landscaping, and lighting were also planned as part of an initial $49 million phase of what could eventually be up to 1.7 million square feet of development on what are now vacant warehouse properties and empty lots.

“By itself, it’s not a critical mass, but it’s really the first piece of the puzzle in terms of getting actual development there,” he said.

The project’s New York-based backers, which include HFZ Capital Group, Arete, and Merchant Equity Group, acquired the four-acre train station parking lot that makes up most of the project site for $2.1 million in mid-2016 from Amtrak and SEPTA. Synterra Ltd. of Philadelphia later joined as a local partner.

Bailkin said the group hopes to begin construction, which is being aided with a $4 million grant from the state’s Redevelopment Assistance Capital Program, in late April or early May.

The developers aim to use local residents and minority- and women-owned businesses for up to 40 percent of its construction crews and operational staff post-completion, he said.