A second night of demonstrations against Belarusian President Alexander Lukashenko turned violent Tuesday as police clashed with students and seriously beat the leader of the main opposition party, witnesses said. Belarus' top police official said 46 people were detained during the protests against Lukashenko, who has ruled this ex-Soviet republic for 10 years and won the right to run for president indefinitely in a Sunday referendum widely criticized as fraudulent. The government's tough tactics continued Tuesday, a day after a protest by some 2,000 young Belarusians in Minsk. Police detained at least 30 people in the crowd of about 300 students who marched down a central street Tuesday evening.