The shooting suspect, Kevin Randleman, 50, of Sandusky, was hospitalized Saturday in Toledo with at least one gunshot wound.
Officer Dunn, 30, had radioed into the office at 3 a.m. to notify dispatchers that he was in the process of making a traffic stop on Tyler Street, between Hayes Avenue and Prospect Street, according to investigators.
As an assisting officer arrived, Officer Dunn and Randleman exchanged gunfire, authorities said.
Numerous gunshots were heard on a recording of the exchange among Officer Dunn, the assisting officer, and the police dispatch office.
"Officer down! Officer down!" the assisting officer shouted over the radio.
"Signal 11," Officer Dunn said into his radio, using a police code for an officer shot. He suffered multiple wounds, police officials said in a news conference at the Erie County Sheriff's Office.
Officer Dunn was taken to Firelands Regional Medical Center, where he was pronounced dead at 4:33 a.m.
Randleman, who lives at 909 West Adams St., suffered at least one gunshot wound, according to the sheriff's office, and was taken by helicopter to the University of Toledo Medical Center, the former Medical College of Ohio, for treatment.
A nursing supervisor Saturday evening would not give any information on Randleman's condition.
Officer Dunn was hired as a reserve officer in 2003 and was promoted to full time in 2008.
At 3 a.m. Saturday, he made a "self-initiated stop" of Randleman, who was riding his bicycle on Tyler, according to Erie County Sheriff's Capt. Paul Sigsworth.
The evidence they collected at the scene included a firearm and multiple shell casings, Captain Sigsworth said.
Radio traffic between Officer Dunn and the dispatcher suggests that Randleman would not stop when the officer made contact with him, Captain Sigsworth said.
Officer Dunn left behind his wife, Julie, and two young children, including a 5-month-old baby, Sandusky police Chief Jim Lang said.
"I'm sorry this happened," Chief Lang said.
"It's a very sad day in the city."
Chief Lang said Officer Dunn was the first Sandusky police officer to be killed in the line of duty.
Officer Dunn's father, Matthew Dunn, is a 20-year veteran of the Sandusky Police Department.
Family and friends filled Officer Dunn's front yard in Sandusky Saturday, cars lining the street.
He was a lifelong resident of Sandusky, graduating from Sandusky High School in 1999. He attended Terra Community College in Fremont, where he received an associate's degree in police science and law enforcement.
He listed golfing, spending time with his family, and being outdoors as favorite activities on his Sandusky Police Department promotional trading card.
He was convicted in November, 1990, by an Erie County Common Pleas Court jury and sentenced to two years in prison for carrying a concealed weapon after being acquitted of aggravated murder and manslaughter in the fatal shooting of Mark Everett in February, 1990.
Charges against Randleman for the shooting had not yet been filed last night.
People who live near Randleman on West Adams Street declined to comment, would not give their name, or said they didn't know him well. One neighbor said Randleman had not lived in his apartment long.
Sandusky police have turned the investigation over to the Erie County Sheriff's Office, which has requested the assistance of the Ohio Bureau of Criminal Identification and Investigation.
Lucas County Coroner's Office is to do the autopsy.
At about 2 p.m. Saturday, Tyler Street was still blocked off as investigators processed the scene. Sandusky Glass Co. was replacing windows that had been shot at during the gunfire; at least seven bullets pierced six windows.
A single white carnation was left in front of a small tree, just in front of the police tape. The neighborhood was silent except for the hum of an engine from a sheriff's sport utility vehicle, and then a voice crackled over a police scanner: "All is clear."
Contact Taylor Dungjen at: email@example.com or 419-724-6054.