The stoppage by the company, a joint venture between Anglo American, BHP Billiton and Xstrata, concerned a month-long wage dispute. For their part, company officials didn’t assign blame to any of the armed groups in the region for the assault.

Prior to the attack, Cerrejón and the coal miner’s union Sintracarbón reached a preliminary agreement to put an end to the strike that started February 7, the parties said in separate statements. The strike caused losses of around 129 billion pesos ($71 million) for the regional and national economy, according to Cerrejón, which said “significant progress” has been made to reach an agreement. The company expects the new labor agreement to be signed at the next meeting.

The text of the new collective contract is being presented to workers for their approval. Workers were initially asking for a 7% pay hike but lowered this to 5.8%, according to a Bloomberg report. The negotiations also involved health and education benefits for workers.