Officials at the Atacama Large Millimeter Array (ALMA) telescope are stepping up security at its construction site in Chile after two researchers were kidnapped on a nearby road.

On 11 March, Rolf Güsten, an astronomer with the Atacama Pathfinder Experiment, an ALMA-related project, and a senior engineer were stopped by four men dressed as policemen on a highway near the site in a remote part of northern Chile. The men commandeered the vehicle and drove it into Bolivia, where a few hours later they left the pair at the side of the road. “Fortunately, none of us was injured,” Güsten says.

ALMA has since increased security by hiring more guards and adding more cameras and phones at the site, and is working with Chilean authorities.