Police are investigating a pair of strong-arm robberies along Interstate 81. Both incidents occurred at rest stops Wednesday afternoon. The first victim was in an RV on I-81 northbound in East Hanover Township when he was approached by about six men, who stole 700 dollars in cash. The second victim was also in an RV on I-81 northbound in Penn Township when a similar incident occurred and he was robbed of a watch and 200 dollars. No one was injured.