ROXBURY TOWNSHIP, N.J. (AP) _ A series of explosions ripped through a gun powder plant early today, injuring at least 15 people and shattering glass in businesses and homes within a 5-mile radius.

The explosions occurred at about 5 a.m. at the Hercules Powder Inc. plant in northcentral New Jersey.

''All I know is that the lights flickered on and off throughout the whole building and in about 15 seconds there was the first explosion,'' said Salvatore Rappa, who was among 80 workers inside the plant.

''Everyone hit the deck and there was a major panic,'' he said, adding that the initial blast in a one-story wooden building set off a chain reaction throughout the plant.

''I felt the whole vibration in my chest,'' Rappa said. ''Debris was coming from the air. It was terrible.''

Fifteen people were taken to Dover General Hospital, about three miles away, hospital spokesman Wayne Schiffner said.

''We've got primarily lacerations, no one who would be termed critical at the moment,'' he said.

The powder plant is located in a semi-isolated area, several miles from several small towns. The plant makes gunpowder for government and commercial use, Rappa said.

''There are windows blown out throughout the area,'' said Sgt. Mike Hass, of the Randolph Police Department, about three miles away from Roxbury Township.

''We're assisting, standing by at the businesses in terms of looting that may occur,'' Hass said.

A resident of Flanders, about five miles away from the plant, said he was awakened by four loud explosions.

''There were four major explosions. It blew me right out of bed,'' said John Larson, who lives in an apartment complex. ''At 5:05 one went off, then three more went off. The blinds blew right out from the window.''