By the time the mayor and top Boston police officers walked into the Eagle Room - packed with reporters - in City Hall on Monday, most had an idea of what announcement was coming.



A Boston Globe report published early Monday morning said Boston Police Commissioner William Evans was set to retire and speculated that next-in-line Superintendent William Gross would replace him.



One person who did not see it coming: Gross' mother.



Sat in the front row, Diana Gross was told her son was receiving a national policing award, not that he would be appointed to the city's top police job. He is the first person of color to do so. She began to cry when the real news was announced.



"My mom is giving me the look," Gross said when he approached the podium. "I could not have done this without my family."



Gross praised his mother who raised three children by herself. She moved her family from "the tough streets of Baltimore" to Boston's Dorchester neighborhood in the 1970s, at the height of the Boston busing crisis, Gross said.



In an interview after the announcement, Diana Gross said she was shocked and proud of her son for breaking a racial barrier in the oldest police department.



"I think that's a great thing, something Willy is really proud of," she said. "Let's hope other people can achieve this. It can happen. He's showing that it can happen."

Gross follows Evans, who will retire in August for a position with Boston College.