Leftist guerrillas hijacked six busloads of people in Medellin Tuesday and harrangued their approximately 300 captives to support a general strike called by a union for later this month, police said. About 100 guerrillas of the National Liberation Army took part, the national police in Medellin, a city of 2.5 million people in northwest Colombia, said in a communique. Drivers and passengers said in broadcast reports that the guerrillas forced the buses to Medellin's outskirts Tuesday morning and made everyone get out and assemble to form an audience. ``They made us listen to a speech in favor of the general strike and against the government's peace proposal,'' bus driver Oswaldo Correa said in a broadcast interview with the Colombian radio chain RCN. The entire episode took about two hours. The guerrillas took the bus keys with them when they left to immobilize the vehicles until police arrived. Colombia's largest labor union, the Workers' Unitary Central, has called a general strike for Oct. 27. It asked guerrillas not to interfere to avoid the strike's leading to violence. The last big general strike in Colombia was in 1977. Police and soldiers fired on rioters in the capital of Bogota, killing 29 people. The Workers' Unitary Central is protesting inflation and is demanding higher wages, a price freeze and an end to right-wing death squads that have killed about 180 union members in the last two years. The inflation rate has been running at about 22 percent. The minimum wage is about $90 a month for a six-day work week. All six of Colombia's leftist guerrilla groups last month turned down a peace plan proposed by President Virgilio Barco. He called for a cease-fire with the nation's estimated 10,000 guerrillas; negotiations, and pardons for all guerrillas who surrendered.