Police are puzzled by reports of booms heard throughout Philadelphia last week.

Investigator Fredesz Moore said reports came in last week from some residents of the Woodland Hills neighborhood about hearing booms late at night.

"We got a call on Saturday about booms around Azalea Drive and Chaney Avenue," he said. "Our officers went out there but couldn't find anything."

Moore added that the sounds might have originated in the country but were picked up by city residents.

Earlier this year it was discovered that a similar boom was caused by an explosive target used to blow up a beaver dam in the Williamsville community.

The targets, which are often available for purchase at pawn shops and gun shows, explode when hit by a high-powered rifle round.