An Oxon Hill man was arrested yesterday on charges of manufacturing explosives after authorities found two pipe bombs, a cache of chemicals and bomb-making paraphernalia in a storage locker over the weekend, Prince George's County fire officials said.

Mark Gerard Spaulding, 29, of the 1000 block of Marcy Avenue, surrendered about 9 a.m. yesterday to fire authorities, Capt. Ron Siarnicki said. His bond was set at $30,000.

Siarnicki said that fire investigators do not have any information linking Spaulding to any bombings in the area.

"He is the only person who knows what his true motives are and he is not saying," said Siarnicki.

Spaulding's attorney could not be reached last night for comment.

Authorities seized the pipe bombs -- three-inch-long metal tubes packed with explosives and "ready to ignite" -- and several hundred pounds of chemicals and powders on Saturday from a U-Store locker on Livingston Road in Oxon Hill, Siarnicki said.

The locker was rented by Spaulding, who had been a customer at the storage facility since 1988, according to authorities and Ozzie Osburn, U-Store manager.

The investigation began, authorities said, after Spaulding allegedly brought homemade fireworks to the Hechinger's store in Fort Washington where he worked and showed them to fellow employees. A spokesman for Hechinger's said that Spaulding's supervisor confiscated the fireworks and notified fire officials.

The spokesman said last night that Spaulding had resigned Friday.

Fire officials said they searched Spaulding's home Friday and found more fireworks and rental receipts that led them to the U-Store locker.

Siarnicki said that most chemicals found in the locker are legal, but that officials found "enough information to indicate that he was mixing them to form explosive devices." It also is illegal in Maryland to possess pipe bombs, he said.

Staff writer Dan Beyers contributed to this report.