Blue lights adorned landmarks around Boston and the Commonwealth Tuesday night for a somber occasion. 

The Department of Transportation announced Tuesday the Zakim Bridge in Boston and the Burns Bridge in Worcester would shine blue in honor of Sean Gannon, a 32-year-old Yarmouth police officer who was shot in the head and killed last Thursday while serving an arrest warrant at a home in Barnstable. Gannon's police dog, Nero, was shot and seriously wounded and is recovering. Gannon was an eight-year veteran of the Yarmouth Police Department. 

Thousands of residents lined the streets of Cape Cod Tuesday as a procession carried Gannon from a funeral home in Hyannis to St. Pius X Church in Yarmouth, where a funeral Mass will be held Wednesday. A private burial will follow. Yarmouth police will stand guard 24/7 until the Mass.

Thomas Latanowich, 29, was charged with killing Gannon and is being held without bail.