A female school bus driver was taking schoolchildren to the Yulupa Elementary School on the morning of October 17th 1969, when she reported that sound of gunfire beside the school bus, stating "As I came around this bend I heard a loud shot from the left hand side of the bus. The children heard it too. Now I don't know if anything struck the bus. We can't find anything that struck the bus". Law enforcement, as usual, were skeptical, pointing out that there was no physical evidence that a shot was fired at the bus. The KRON news footage stated that law enforcement were expecting more reports of this kind based upon the Zodiac Killer's latest letter regarding the murder of Paul Stine. The newspaper report in the San Francisco Chronicle about the Santa Rosa bombing threat on school buses wasn't released until October 21st 1969, so a school bus driver reporting shots heard alongside her school bus in Santa Rosa four days earlier, should be considered of some significance. Also, this bus driver was transporting schoolchildren on the morning of October 17th 1969 - the same morning that the Zodiac Killer's threat on schoolchildren was released in the newspaper.
So, if the Santa Rosa school bus shooter wasn't the Zodiac Killer, we would have to believe a random individual bought the San Francisco Chronicle on the morning of the 17th, read about the "picking off kiddies as they came bouncing out" of a school bus, and almost immediately positioned themselves on a Santa Rosa street or road, from where they started shooting at a school bus (assuming the bus driver's claims are accurate). Were law enforcement suggesting that this elderly woman school bus driver bought and read the Chronicle newspaper before collecting the schoolchildren that morning and just invented the story to mirror Zodiac's threat? While this is unlikely but possible, she could have had no knowledge of the Zodiac Killer's phone call to Santa Rosa threatening school buses and schoolchildren on October 15th 1969. Bearing in mind (in the relevant timeframe) that this currently is the only reported shooting with respect to a school bus that we know of, it seems unusual that it should somewhat mirror the threat two days earlier in the same location. Unfortunately, law enforcement regularly dismissed things as hoaxes, as they did with the Oklahoma radio station recording of a man claiming to be the Zodiac Killer on December 7th 1969. Passing things off as hoaxes seems a tried and trusted method of doing absolutely no work.
This lends greater credence to the claim by Robert Graysmith in his "Zodiac" book that "A man identifying himself as Zodiac had made a Santa Rosa Bomb threat exactly a year earlier". In other words, Graysmith claimed that on May 8th 1969 (before the Zodiac pseudonym was known) somebody had aimed another bomb threat at Santa Rosa. This possible threat encompassing Zodiac, telephoned bomb threats and Santa Rosa would come four months before the October 15th 1969 telephone call encompassing Zodiac, bombs and Santa Rosa. An October 15th 1969 telephone call to Santa Rosa threatening schoolchildren on school buses, that was made two days in advance of the Zodiac Killer's threat to pick off kiddies as they came bouncing off the school bus, which wasn't currently known to the public when the October 15th call was made.
If Graysmith was correct about somebody claiming to be the Zodiac Killer on May 8th 1969, this K-Mart bomb threat (or threat to another entity in Santa Rosa) would have come just over one month after the last major newspaper article about the Lake Herman Road murders (March 30th 1969). This Sunday Times-Herald article read "The horrifying crime may very well be the most celebrated murder mystery currently under investigation in California, and Lunblad has received aid and offers of it from a score of law enforcement agencies in the state. Those which have given him particularly large measures of support include the Vallejo Police Department, his own sheriff's department, the Benicia Police Department, the Napa and Sanoma County sheriff's departments, and the Fairfield Police Department". All these police departments would become the focus of the Zodiac Killer's murders and threats in the following months. The county seat and largest city in Sanoma County is Santa Rosa, the focus of the K-Mart bomb threat by somebody claiming to be the Zodiac Killer on May 8th 1969. Vallejo and Napa County both saw the wrath of Zodiac when he attacked at Blue Rock Springs and Lake Berryessa, with the two Fairfield letters in December threatening the promise of further attacks. Every police department mentioned in this newspaper article as helping Sergeant Les Lunblad would receive the attention of the Zodiac Killer.