Authorities in West Haverstraw are still investigating the Monday afternoon blast that demolished a townhouse and sent two firefighters and two O&R workers to the hospital with major injuries.

(Read Patch's live coverage of the incident here.)

The explosion—caused by a ruptured natural gas main at around noon—left one family homeless; hundreds of other residents were evacuated. Currently, Haverstraw Police are continuing to study the incident.

The Rockland County Sheriff's Department was also in the rubble investigating Monday, a spokesman said, but is not at the scene Tuesday.

The two volunteer firefighters who were injured in the blast, Jerry Knapp and Ken Patterson, suffered burns and broken bones. They were just outside the house when it exploded—knocking on doors and warning residents to evacuate—and were thrown by the force of the blast and seared by heat. LoHud is reporting that Knapp has been released from the hospital.

West Haverstraw Fire Chief George Zayas said the disaster could have been much worse had firefighters not begun an evacuation of the area immediately upon arriving.