A cab driver was held up at knifepoint by his passenger and robbed of an unknown amount of cash on the 5800 block of Quantrell Ave. March 10, authorities say. 
    
The driver picked up the passenger, described by police as a Hispanic woman in her 20s, in Arlington and bound for Quantrell Avenue. When they arrived at about 1:38 a.m., the woman put a knife to his throat and demanded all of his money, police said. 
    
She left the cab and walked toward a nearby apartment complex after taking the cash, leaving the driver with minor injuries, officials said.