The article doesn't elaborate, but presumably, the police convoy relates to the hostage situation: > But Dr. Grimalda said his fieldwork had lasted seven weeks

The article doesn't elaborate, but presumably, the police convoy relates to the hostage situation: > But Dr. Grimalda said his fieldwork had lasted seven weeks longer than expected, partly due to a volcanic eruption and security threats; he said he was held hostage by a group of machete-wielding bandits