CENTENNIAL, Colo. — A student who went to his suburban Denver high school Friday armed with a shotgun and looking for a specific teacher shot two students, including one critically, before apparently killing himself, the local sheriff said."The teacher began to understand that he was being looked at and exited the school. One student confronted the armed student and was shot," Arapahoe County Sheriff Grayson Robinson said.One of the wounded students, a girl, was in serious condition, Robinson said. The other student suffered minor injuries and was expected to be released from the hospital Friday night, he said.A suspected Molotov cocktail was also found inside Arapahoe High School, the sheriff said.