The owners of a home that exploded in western Pennsylvania last weekend were having issues with their hot water tank, authorities said, but the cause of the blast that killed five people — including two municipal officials — remains under investigation.

The explosion in Plum destroyed three structures and damaged at least a dozen others. It occurred shortly before 10:30 a.m. Saturday at a home owned by Heather Oravitz, the town’s community development director, and her husband. The town is about 20 miles (32 kilometers) east of Pittsburgh.

Plum Mayor Harry Schlegel said Oravitz, 51, and Plum Borough Manager Michael Thomas, 57, were killed in the blast, along with three others who lived in the neighborhood: Kevin Sebunia, 55; Casey Clontz, 38; and Clontz’s 12-year-old son, Keegan.