Baltimore County officials said Wednesday a new $300 million development of stores, offices and residential units in Towson will fill a void — and nearly an entire city block — to create what County Executive Kevin Kamenetz called "an urban centerpiece."

The privately funded Towson Row project on about five acres off busy York Road will include more than a million square feet of mixed-use space.

Arthur Adler, principal in the developer, Caves Valley Partners, said Towson Row would help Towson become "every bit as vibrant and successful an urban core as places like Bethesda or Harbor East."

"We intend to do our part in helping Towson achieve its full potential," he said.

Towson Row's overall space will be roughly the equivalent of the nearby Towson Town Center mall, but with a different mix: 200,000 square feet of offices, 350 high-rise apartments and condominiums, 300 student housing units, 200 extended-stay hotel units and more than 100,000 square feet of retail, restaurants and what officials called an "upscale" grocer. The plan also includes more than 1,000 garage parking spaces.

No prospective tenants were announced Wednesday.

The properties involved — several businesses and a large parking lot — are all within Towson's business core, and carry zoning designations that allow for what's being proposed. Towson Row will undergo a county planning review with opportunities for public comment, but no zoning changes are needed.

Kamenetz said the county seat "deserves a great, vibrant downtown," and touted Towson Row as a "transformational private investment."

That transformation will come over several years. In January, it was announced that Caves Valley had acquired the properties, but Adler said construction won't begin until 2015.

When it does, companies leasing space in many of the existing buildings along Chesapeake, Susquehanna and Washington avenues will be displaced as those buildings are demolished. A few businesses at the corner of York and Chesapeake, including a convenience store and several restaurants — 7West Bistro, the Orient and Miller's Deli — will be untouched, Adler said.

Towson Chamber of Commerce Executive Director Nancy Hafford, who is also a member of the county's Planning Board, said the chamber is already working with owners of member businesses to keep them in Towson.

"We've already got people talking to property owners, negotiating leases," she said.

Teri Weatherly, a resident of West Towson, opened Tease Me Salon at 13 W. Chesapeake Ave. four years ago, and said she has six years left on her original 10-year lease. Her building was one of many purchased by Caves Valley Partners for the project. She said she'd like to stay, but doesn't know what will happen.

"I told them I have a six-year lease, and want to fulfill my plan," she said. "I've been waiting for progress to come [to Towson], but I didn't know I'd be part of ground zero."

For the businesses that stay in town, the development will mean more customers, Hafford said.

"Instead of having people who are going to be working here Monday to Friday, nine to five, we're going to have thousands of people living in the core of Towson supporting businesses 24 hours a day," she said.

That opinion was echoed by Katie Pinheiro, executive director of the Greater Towson Committee, a group that advocates for Towson and advises developers on projects there.

"It seems that it's going to get people in Towson, and it's going to get people to stay in Towson," she said.

Wednesday's announcement was not without some concern about additional development in Towson — and its effect on traffic. Greater Towson Council of Community Associations President Paul Hartman said the Towson Row plan is "a lot to digest. Certainly, we need to accelerate discussions on traffic issues."

County Councilman David Marks, a Republican who represents the 5th District, including Towson, called the project "probably the boldest development we will ever see in downtown Towson," and said it could help prompt creation of a shuttle service in Towson.