FUZHOU, June 21 -- Four students were injured, including one in critical condition, when a man wielding a knife broke into a school in Fuzhou, capital of southeastern China's Fujian Province, local police said late Wednesday.The young man broke into a classroom of the high school affiliated to Fujian Normal University at 1:10 p.m. Wednesday and slashed the students with his knife.A teenage girl was in critical condition, and the other three were out of immediate danger.The four victims are all grade-two students in the high school.The man has been arrested and is being interrogated by police.