CAMDEN - (AP) - Authorities say a 6-year-old boy was stabbed to death inside his southern New Jersey home, and his 12-year-old sister is critically wounded.

A suspect was being sought, but it's not clear yet why the children were targeted early Sunday.

Camden County prosecutors say it appears the children were stabbed while together in an upstairs bedroom in their home in Camden, a city across the river from Philadelphia that continually ranks as one of the nation's most dangerous. The girl, whose throat was slit, went door to door to get help and a neighbor called 911.

Two other girls, age 9 and 14, also were in the home but were not injured. The 14-year-old had been baby-sitting the other children because their mother was in the hospital.