Earlier, relatives confirmed to the Morning Call of Allentown that a man and his 2-year-old son were among the casualties. The relatives confirmed multiple reports on social media. Agents from the Bureau of Alcohol, Tobacco and Firearms are conducting the investigation.
In a news conference Sunday, authorities told reporters they believe the explosion was an isolated incident and that there is no continuing public threat, WPVI reported.
"We know there's been a criminal incident," District Attorney James Martin said during a news conference Sunday, according to an Associated Press report. "We have a high degree of confidence that the perpetrator was probably killed in the incident."