POTTSTOWN, Pa. (AP) — At least four people have been killed and others might still be missing after a house explosion in a suburb northwest of Pennsylvania, authorities said.

Pottstown Borough Manager Justin Keller confirmed in a press conference that the explosion occurred Thursday just after 8 p.m. in Pottstown, about 40 miles (64 kilometers) northwest of Philadelphia, WPVI-TV reported.

Two other people were hospitalized, Keller said. Their conditions are unknown.

It is not immediately known what caused the explosion. Police have not yet named those who were killed or injured in the explosion. No additional details have been released.