NBC October 24, 2019 5:15 pm Playground Opens in Memory of Sean Gannon A police sergeant killed in the line of duty is being honored with a memorial playground. US & World Videos 1:43 Authorities respond to incident in Northbridge 0:49 Bowling alley reopens 6 months after mass shootings in Lewiston, Maine 2:27 Mother speaks out after school shooting threat in Milton 0:17 Student encampments taken down at Tufts University 1:46 Deaf woman stabbed in East Boston