Mexican authorities said Friday they have detected and seized 24 drug cartel surveillance cameras fixed to telephone and light posts in the border city of San Luis Rio Colorado. The city on the border with Arizona has suffered years of violence between drug cartels fighting for control of the border crossing, where they can smuggle drugs. Prosecutors in northern Sonora state said the cameras had been placed there by “falcons,” the name commonly used in Mexico for drug cartel lookouts seeking to keep tabs on the movements of soldiers and police.