Two attacks on busses in El Salvador over the weekend left 13 people dead, dpa cited La Prensa Grafica newspaper as reporting today. Unidentified attackers on motorcycles stopped a bus and set it on fire north of the capital San Salvador, killing 11 people and injuring at least 12 others. A short time later four armed attackers stormed another bus a few hundred metres away and killed a young girl and a ticket collector. Three other passengers were injured. Police believe the attackers in both incidents are members of the gang known as 18 and said the alleged motive was extortion of the bus company. Six suspects have been arrested, national police director Carlos Ascencio said. Catalino Miranda, president of a group composed of the country's transportation companies, spoke out against constant demands from criminals that companies pay protection money to prevent attacks on their vehicles.