LANCASTER, Pa. — The National Transportation Safety Board has not identified the cause of a Pennsylvania home explosion that killed a utility worker and injured three others.

In a preliminary report released Tuesday, the NTSB says a tapping tee leading to the Manor Township home was leaking gas. However, the board says the service line to the home was not leaking.

Richard Bouder died of multiple injuries from flying debris in the July 2 blast. UGI Utilities says the 54-year-old man was one of three employees working outside the home when the explosion occurred.

The other two employees and a sewer worker were hospitalized for non life-threatening injuries.

The home’s gas meter, three tapping tees and other materials have been shipped to an NTSB lab for further testing.