A head-on collision Tuesday on North Main Street sent two people to the hospital with injuries that were not considered life-threatening, according to a police spokesman, Lieutenant Tilden Kaufman.  Shortly after 8 a.m., the vehicles were traveling in opposite directions on North Main Street, which is Route 27, when one crossed the center line and hit the other near the corner of Canton Street. The road was temporarily closed. Alcohol was not involved, said Kaufman, who said that the accident was still under investigation and charges would likely be filed. The lieutenant said one vehicle was registered to a Sharon resident and one to a Canton resident.