A Toronto police officer on a lunch break during training was shot and killed in Mississauga by a suspect who was later arrested in Hamilton after a second fatal shooting, authorities said at a media briefing Monday night.   

  Authorities said another person was injured in Mississauga.  The suspect fled into Milton and is believed to have shot three other people, killing one, police said.   

  Constable Andrew Hong, 48, of the Toronto police traffic unit was shot at close range and died at the scene, Chief James Ramer told reporters.   

  “This is devastating news for his family and for all members of the Toronto Police Service and our entire police community,” the chief said.  “We will lean on each other as we work to support Constable Hong’s family and each other in our grief.”   

  Hong is survived by his wife and two children.  He was with the department for 22 years.   

  Peel Regional Police in Mississauga said earlier they were called to the scene of a shooting that took place at the intersection of Argentia Street and Winston Churchill Avenue, where two people were shot shortly after 2 p.m.  ET.   

  The victim who was taken to hospital has “life-changing injuries” and is in a trauma centre, Peel Regional Police Chief Nishan Duraiappah said in the update.  He described the shooting of the constable as an ambush.   

  After the suspect fled, three people were shot on Bronte Street South in neighboring Milton, Halton Regional Police said.  According to police, one person was pronounced dead at the scene and two others were taken to hospital.  Their conditions were not immediately available.   

  “We believe this was the same suspect that was involved in the shooting here in Mississauga,” Duraiappa said.   

  The suspect — who Peel police said was wearing all black with a yellow construction vest — was taken into custody, according to Halton Regional Police.   

  Both police agencies said they are investigating the connection between the two incidents and believe they are linked to the same person.   

  Prime Minister Justin Trudeau tweeted about the shooting late Monday.   

  “My thoughts, and the thoughts of many others, are with all those who knew the police officer killed in the line of duty in Mississauga today,” Trudeau tweeted.  “Our thoughts are also with those injured in today’s shootings – we wish you a full recovery.”   

  Milton, Mississauga and Hamilton are not far west of Toronto.