Several unions went on strike Monday, including teachers and miners, and students marched into downtown Niamey to protest the killing of three students by police last week. President Ali Saibou's military Cabinet, continuing an emergency meeting begun over the weekend, praised ``the valor of the forces of law and order'' who opened fire Friday to disperse a rally of about 3,000 high school and university students. The government says police killed three people and wounded 33. Students put the death toll at 12. A government statement said the Cabinet ordered all secondary schools and Niamey University closed. Police did not interfere with Monday's march. The students also denounced the World Bank, International Monetary Fund and government for an unpopular austerity program that was a causes of Friday's demonstration. Saibou's government said in its statement the Cabinet ordered an investigation ``to unmask agitators and trouble-makers.'' It claimed students were being manipulated by ``traitors to the national cause pursuing personal ambitions.'' Striking teachers said they also were protesting the arrests of two colleagues detained on suspicion of encouraging student unrest. Leading politicians invited to the Cabinet meeting said the government had agreed to meet with student representatives. No date was given. In the past, the government has accused students of being greedy in demands for larger grants, better-equipped libraries and laboratories and guarantees of government jobs. The government has put a freeze on public jobs. Government officials say the demands are excessive in one of the world's poorest nations. The unrest is the worst in Niger since Saibou won a new seven-year term Dec. 10.