Bomb rips through Manhattan: Twenty nine hurt, one critical as 'homemade IED' rocks Chelsea and a second device is found in a PRESSURE COOKER - hours after bombing at military fun-run .
Police responded to explosion in Chelsea neighborhood at West 23rd and Sixth Avenue around 8.30pm
Hundreds of people were fleeing the scene down the block as police cordoned off the area
At least 29 people were reported injured by the Fire Department but injuries don't appear life-threatening
Police have said cause of blast is unknown as bomb sniffing dogs search for remnants of a possible bomb
NYPD Special Ops tweeted that they are investigating a 'possible' second device found four blocks away
The device is reportedly a 'pressure cooker' wrapped in plastic with a cell phone or timer attached to it
CCTV footage shows blast ripping through New York's affluent Chelsea neighborhood as people passed by
Mayor Bill de Blasio said during press conference that authorities believe it was an 'intentional act'
The NYPD tweeted that people should stay away from windows facing 27th Street until the area is clear
NYPD has increased security across the city following the blast Saturday night as a precaution
Subways in the area have been shut down because of the explosion, authorities said