A former school bus driver in southern New Hampshire and Maine has pleaded guilty to sexually exploiting children on his bus. Milton, N.H., resident John Allen Wright was arrested last fall and charged with filming child pornography on the bus using cameras hidden in glasses and pens. The 46-year-old worked as a bus driver for special needs children. Federal prosecutors say a search of Wright’s home and computer uncovered several videos showing him sexually assaulting children who were passengers aboard his bus and thousands of child sexual assault images downloaded from the Internet. Wright pleaded guilty on Tuesday to six counts of sexual exploitation of children. He faces a mandatory prison term of 15 years on each of five counts and a total maximum sentence of up to 160 years.