In less than 10 seconds on Saturday, a slice of North Philadelphia changed forever.

Not long after sunrise, the Philadelphia Housing Authority demolished two high-rise towers that are part of the Norman Blumberg Apartments, a half-century old public-housing complex in the city's Sharswood section.

The arrowhead-shaped neighborhood sits roughly between Girard and Cecil B. Moore Avenues, from 19th to 27th Streets.

Saturday's spectacle was a symbolic, but also very real piece of a $500 million, decade-long plan PHA hopes will transform an extremely poor neighborhood with a history of drugs and violent crime.

"This is the next big step towards delivering on our promise to the Blumberg/Sharswood community. Life as we know it is going to change. It will be forever changed by removing the stigma that was created by this high-rise," said PHA president Kelvin Jeremiah before the 18-story towers came down.

For former Blumberg resident Timothy Mack, watching the high-rises disappear was bittersweet.

"It's sad to see them go, but I'm glad they're changing the neighborhood," said Mack. "The way things are around here now, we need change."

Before the implosion, Jeffrey Glenn gazed at the towers. He's lived in Sharswood for all of his 44 years and like Mack, thinks getting rid of them will improve the neighborhood.

He's less confident about PHA's plans moving forward.

"They have an ambitious plan, but I don't know if it's going to come to fruition," said Glenn. "I want to see them go through with it."

The tower for senior citizens is now the only high-rise sitting along the Blumberg superblock at 23rd and Jefferson Streets.

The 306 units comprising the so-called family buildings will be replaced during the project. Ditto for the 108 low-rise units part of the complex, which will also be demolished.

Under the plan, PHA is expected to acquire more than 1,300 properties in the neighborhood - roughly 800 through eminent domain. The land will be used for both residential and commercial development. The agency will use some 300 parcels to build a brand new headquarters.

At the end of a ceremony before the demolition, State Rep. Curtis Thomas applauded the project, but also shared a warning of sorts.

"I ask each and every one of you, resident, presidents, tenants, let's make sure that as this dream become a reality, that we make sure that, on the inside of the dream, that we raise our kids and support one another in a way that makes this Sharswood/Blumberg the best community in the city of Philadelphia," said Thomas.

PHA has been short on details about how it will pay for the ambitious project. Some residents complain that they have to live amid demolition because of delays in getting relocated. PHA is promising to resolve those issues.