Residents gathered in sanctuary of the Our Lady of Queen of Peace Church.
Three lit candles represented each of the victims: David Fleetwood, Gerard Kozic and James LaGuardia.
Mourners then lit candles to represent the bright light the men were in the community.
Earlier Thursday, Pennsylvania Governor Tom Corbett ordered some state flags lowered in memory of the victims.
Monday's tragedy "strikes at the heart of America's tradition of hometown democracy," Corbett said. "Pennsylvania has lost three good citizens who were at a township meeting to exercise their constitutional right to self-government."
Police said Rockne Newell was angry at Ross Township officials after losing his junk-strewn property in northeastern Pennsylvania last month in a court fight and opened fire at a building where they were meeting. Authorities said he had told his father and others he had nothing left to lose and planned to kill township officials.
Newell faces charges that include three homicide counts. He didn't enter a plea at his arraignment Tuesday. When a judge asked him at the arraignment if he owned any real estate, he replied, "They stole it from me. That's what started all this."
Newell, a 59-year-old disabled junk dealer, had feuded with officials for years over longstanding complaints that he lived in a storage shed, built an illegal culvert and used a bucket outside as a toilet on his property.
On Monday night, police said, he fired a barrage of rifle shots through a wall into the meeting room before entering the room and shooting a supervisor and four residents. He then retreated to his car, retrieved a revolver and returned to the meeting room, where he was tackled by two men and shot in the foot during the scuffle, police said.
Two residents died at the scene, and the township zoning officer died after being after being flown to a hospital.
The governor ordered that state flags be lowered for three days at the Capitol complex in Harrisburg and at state facilities in Monroe County, beginning Sunday. His spokeswoman Kirsten Page said that is when the first of the victims' funerals is scheduled.
U.S. and Pennsylvania flags already are flying at half-staff to mark the July 28 death of former Gov. William Warren Scranton. The flags are scheduled to be returned to full staff on Wednesday, when a memorial service is scheduled in the city named after his family.
The Associated Press contributed to this report.