Authorities said Latanowich fatally shot Gannon in the head as the officer chased him into the attic of his home.
The officer was taken to Cape Cod Hospital with life-threatening injuries, according to WCVB5.
"We're going to miss him terribly, our department is going to miss him terribly", said Police Chief Frank Frederickson. He called Gannon a "remarkable young man". "And I'm not just saying that".
Latanowich has an prolonged historic previous of run-ins with regulation enforcement and was linked to 111 prior jail charges, police talked about in a Fb submit.
Agawam Police Department: "Our thoughts & prayers go out to his family and also to his brothers & sisters in blue at Yarmouth PD". The Yarmouth Police Officer was shot and killed today protecting his community from a unsafe person.
A vigil began just after 7 p.m. Saturday near the Yarmouth Police Department.
Gannon's police vehicle has been parked outside the Yarmouth Police Station, and residents visited on Friday to pay their respects and lay flowers on the car's hood.
Newton police, Federal Bureau of Investigation looking for bank robbery suspect
A hotel guest sitting in his auto heard the woman scream, and then saw the suspect running with a purse and jump into a gold SUV. Investigators say the suspect entered the business armed with a handgun, assaulted a female employee and demanded money.
State police say Gannon's police dog was injured.
"Officer Gannon truly was among the best of the best on the department".
"We're in our vehicle, just driving around because we can't go back home". He then graduated with honors from Westfield State University in 2007 with a bachelor of science degree in criminal justice. "Officer Sean Gannon was killed in the line of duty today".
Latanowich, of Somerville, was taken into custody after an hour-long standoff.
The suspect appeared in court on Friday and pleaded not guilty to murder.
Western Mass News will provide updates to this as more information becomes available.