Authorities: Crime not ruled out in Texas blast

One month after a fire triggered a massive blast at a Texas fertilizer plant that killed 15 people, officials on Thursday had to declare the cause of the blaze as "undetermined."

Investigators narrowed the number of possible causes to three: a problem with one of the plant's electrical systems, a battery-powered golf cart, and a criminal act. They ruled out a wide number of others, from a rail car on site loaded with fertilizer to someone smoking. (AP)