Regular public transport users get to know the standard euphemisms. In Melbourne, "due to a police request" means that someone is threatening to jump in front of a train, "due to a police operation" means that someone has done it :-(.
Yikes. The MBTA alerts are often quite descriptive -- Melissa was delayed yesterday due to "an unauthorized person on the tracks". I think they delays would have been worse had there also been a police operation.