Police have made one arrest so far in the July 2 shooting in the city's Fruit Belt neighborhood that killed a 17-month-old boy and his grandmother and wounded two men.
But investigators believe more people were involved in the shootings.
Law enforcement authorities are reminding the public of a reward of up to $25,000 being offered, in addition to a separate $4,000 reward from Crime Stoppers Buffalo, for information leading to the arrest of whoever was involved in the shooting.
"The reward is still active as we believe there were additional people involved in this crime," said Buffalo Police Capt. Jeff Rinaldo.
"We want to make sure that we remove all of the people who may be responsible for those homicides from the streets of Buffalo," said FBI Buffalo Special Agent in Charge Gary Loeffert. "Anyone capable of committing a crime of that nature should not be walking the streets of Buffalo."
The $25,000 reward comes from the FBI, which is working with Buffalo police to investigate gang-related violence in the city. Officials say the reward money is among the most ever offered in a Buffalo homicide case.
At about 12:30 a.m. July 2, Yvette Johnson and her grandson Kyrie were killed on the front porch of her home on Grape Street. Yvette Johnson had just celebrated her 54th birthday with her family that night and she was getting ready to move to Georgia where she had a new job.
Police called the quadruple shooting a "horrific, horrific crime" and implored the public to come forward with information to help them catch the killers.
Late last month, authorities announced that a grand jury indicted Kenyatta Austin, 25, of Buffalo, on murder, assault and other charges. He had been arrested a month earlier in Niagara Falls on a gun possession charge.
"We still need more people to come forward," Deputy Police Commissioner Joseph A. Gramaglia said in August. "We're hoping people see that an arrest was made here and now will feel even more comfortable coming forward and talking to us."
The FBI asked anyone with information to call the bureau at 716-856-7800 or the Buffalo Police confidential TIP CALL line at 847-2255.
Crime Stoppers can be reached at 716-867-6161 or through the Crime Stoppers Mobile App which can be downloaded to a cell phone through Apple or Android stores.