KOLLAM: The members of the pro-Congress Kerala NGO Union (Kambara) and the pro-LDF Action Council of State Employees and Teachers clashed at the District Treasury inside the civil station complex here on Saturday. Four employees were injured. Two of them were hospitalised. The Kollam West police have registered a case. Trouble erupted when both the groups reached the District Treasury at the same time. While the council members campaigned to make the January 24 employees' strike a success, the association members campaigned against the strike.