Four people were killed and at least one more is missing in a western Pennsylvania apartment building explosion that destroyed three structures and damaged at least a dozen others on Saturday morning local time, The Associated Press reports, citing local authorities.

The explosion occurred in the Plum area, about 32 kilometers east of Pittsburgh.

Officials informed journalists at the scene that they did not have precise information about who was at home and who might have had visitors at the time of the explosion, so they were unable to provide an exact number of individuals who are considered missing.
The cause of the explosion is being investigated.