The Boston Globe took an in-depth look at the problem of gas leaks in March 2009 after a series of home explosions. According to the Globe's account, three Massachusetts homes and one in New Hampshire were struck by explosions between December 2008 and March 2009. The Globe said, "These blasts, killing three and injuring one, have served as a reminder of the dangers associated with the massive underground pipe system tunneling beneath streets and delivering a flammable product to nearly 1.5 million customers in the state." The Globe investigated gas explosions dating back to 2004 and found that thousands of gas leaks occur each year. Causes include old, corroded pipes, construction accidents and human error, the paper reported.