While most Americans were polishing the grill and shopping for fireworks, the National Transportation Safety Board (NTSB) was responding to six general-aviation airplane crashes, a natural-gas pipeline explosion and an engine fire on a commercial airliner during Saturday and Sunday of the Independence Day weekend.

• The NTSB dispatched an investigator to Denver to assess the damage to a CRJ-700 following an engine fire Sunday. The assessment will determine the scope of any potential NTSB investigation.
• The NTSB sent two investigators to Millersville, Pennsylvania, where a utility worker was killed and three others injured while investigating a natural gas leak Sunday. One home was destroyed and four others damaged.

The Board also is actively investigating the following general aviation accidents that occurred during the weekend:

• Catawba, Wisconsin – Six people were fatally injured Saturday in a Cessna C421 crash. The airplane was traveling from Waukegan, Wisconsin, to Winnipeg, Canada, when it crashed following a report to air traffic control of poor weather in the vicinity. The debris field suggested an in-flight breakup.
• Chatsworth, Georgia – Four people were fatally injured Saturday in an in-flight breakup of a Piper PA-23 flying from Auburn, Alabama to Tennessee. Thunderstorms were observed in the area.
• Chelan, Washington – Two people were fatally injured in a Scout XC Light Sport that crashed 8 miles NE of Chelan. The aircraft, which crashed on Saturday, was located on Sunday.
• Monticello, Iowa – The pilot of a Flight Design CTSW LSA was fatally injured Saturday when the airplane hit terrain.
• Linesville, Pennsylvania – One person was fatally injured Sunday following the crash of an Experimental Slip Stream Gennis, a half-mile from Merry’s Pymatuning Airport.
• Irvine, California – Two people were injured when a Cessna 310R reported engine problems and crashed onto the 405 freeway Friday.