Pickering described Chiapperini as a "lifetime firefighter" with nearly 20 years in the department, and he called Kaczowka a "tremendous young man."
Kaczowka's brother, reached at the family home Monday night, said he didn't want to talk.
The two wounded firefighters, Joseph Hofstetter and Theodore Scardino, were in guarded condition in the intensive care unit at Strong Memorial Hospital, authorities said. Both were awake and alert and are expected to recover.
Hofstetter, also a full-timer with the Rochester Fire Department, was hit once in the pelvis, and the bullet lodged in his spine, authorities said. Scardino was hit in the chest and knee.
At West Webster Fire Station 1, there were at least 20 bouquets on a bench in front and a bouquet of roses with three gold-and-white ribbons saying, "May they rest in peace," ''In the line of duty" and "In memory of our fallen brothers."
A handwritten sign says, "Thanks for protecting us, RIP." Two candles were lit to honor the dead.
Grieving firefighters declined to talk to reporters. At an impromptu memorial vigil Monday evening, about 100 people stood in the cold night air, some holding candles. A fire department spokesman made a brief appearance, thanked them all and told them to go home and appreciate their families.
Cathy Bartlett was there with her teenage son, who was good friends with Kaczowka. Bartlett's husband, Mark Bartlett, has been a firefighter there for 25 years but missed the call this morning.
"Thank God my husband slept through the first alarm and didn't get up until the second one went off," she said.
The shooting and fires were in a neighborhood of seasonal and year-round homes set close together across the road from the lakeshore. The area is popular with recreational boaters but is normally quiet this time of year.
"We have very few calls for service in that location," Pickering said. "Webster is a tremendous community. We are a safe community, and to have a tragedy befall us like this is just horrendous."
O'Flynn lamented the violence, which comes on the heels of other shootings including the massacre of 20 students and six adults at Sandy Hook Elementary School in Newtown, Conn.
"It's sad to see that this is becoming more commonplace in communities across the nation," O'Flynn said.
Gov. Andrew Cuomo said the State Police and Office of Emergency Management were working with local authorities.
"Volunteer firefighters and police officers were injured and two were taken from us as they once again answered the call of duty," Cuomo said in a statement. "We as the community of New York mourn their loss as now two more families must spend the holidays without their loved ones."
Webster, a middle-class suburb, now is the scene of violence linked to house fires for two Decembers in a row.
Last Dec. 7, authorities say, a 15-year-old boy doused his home with gasoline and set it ablaze, killing his father and two brothers, 16 and 12. His mother and 13-year-old sister escaped with injuries. He is being prosecuted as an adult.
Associated Press writers Chris Carola, George Walsh and Mary Esch in Albany contributed to this report.