Police in Mexico City say they caught five alleged extortionists in Iztapalapa after interrupting an assault and chasing a pink-and-white taxi through Barrio San Antonio. The arrest, made public Thursday, fits a broader pattern: extortion is rising and becoming more brazen. One suspect already had a prison record for the same crime. Here is what happened on the street, what authorities seized, and how this case sits inside a larger fight against …