TOKYO—Three people, including two students on their way to take university entrance exams, were stabbed Saturday just outside of a test venue, and authorities arrested a 17-year-old student at the scene on suspicion of attempted murder, Tokyo police said. The victims—two 18-year-old high school students and a 72-year-old man—were all conscious and their injuries were not life-threatening when they were rushed to a hospital for treatment, police said. But the elderly victim was later in serious condition, local media reported. Police said the attacker, who was identified only as a high school student from the central Japanese city of Nagoya because he is a minor, slashed the three people in their back on a street just outside of the University of Tokyo’s main campus, one of the venues for Japan’s two-day nationwide entrance exams this weekend. Police said they are investigating the attacker’s motives. He was not taking the exam. …